Picture partitioning-based coding method and device

ABSTRACT

An image decoding method performed by a decoding device according to the present disclosure comprises the steps of: receiving a bitstream containing at least one of segmentation information of a current picture and prediction information for a current block included in the current picture; deriving a first segmentation structure of the current picture, which is based on multiple tiles, on the basis of the segmentation information of the current picture including at least one of information of the number of width-parsing columns, information of the last width, information of the number of height-parsing rows, and information of the last height; deriving a block predicted for the current block, on the basis of the prediction information for the current block contained in one of the multiple tiles; and generating reconstruction samples for the current block on the basis of the predicted block.

BACKGROUND OF DISCLOSURE Field of the Disclosure

The present disclosure relates to an image coding technology and, moreparticularly, to a picture partitioning-based coding method andapparatus in an image coding system.

Related Art

Recently, the demand for high resolution, high quality image/video suchas 4K, 8K or more Ultra High Definition (UHD) image/video is increasingin various fields. As the image/video resolution or quality becomeshigher, relatively more amount of information or bits are transmittedthan for conventional image/video data. Therefore, if image/video dataare transmitted via a medium such as an existing wired/wirelessbroadband line or stored in a legacy storage medium, costs fortransmission and storage are readily increased.

Moreover, interests and demand are growing for virtual reality (VR) andartificial reality (AR) contents, and immersive media such as hologram;and broadcasting of images/videos exhibiting image/video characteristicsdifferent from those of an actual image/video, such as gameimages/videos, are also growing.

Therefore, a highly efficient image/video compression technique isrequired to effectively compress and transmit, store, or play highresolution, high quality images/videos showing various characteristicsas described above.

SUMMARY

This disclosure is to provide a method and apparatus for improving imagecoding efficiency.

This disclosure is also to provide a method and apparatus for signalingpartitioning information.

This disclosure is still also to provide a picture partitioning methodand apparatus based on signaled information.

This disclosure is still also to provide a method and apparatus whichpartition a current picture, based on partition information for thecurrent picture.

This disclosure is still also to provide a method and apparatus whichdetermine the width (or height) of each of length parsing skip tilesamong a plurality of tiles constituting a current picture, whoseinformation on width and height is not parsed, based on the last width(or height) among the signaled widths (or heights).

According to an embodiment of this disclosure, an image decoding methodperformed by a decoding apparatus is provided. The method includesreceiving a bitstream including at least one of a partition informationfor a current picture and a prediction information for a current blockincluded in the current picture, deriving a first partitioning structureof the current picture, based on the partition information for thecurrent picture, wherein the first partitioning structure of the currentpicture is based on a plurality of tiles, and wherein the partitioninformation for the current picture includes at least one of informationon a number of width parsing columns among a plurality of columns forderiving the first partitioning structure, whose information on width isparsed, information on a last width indicating a width among the widthsof the width parsing columns, which is parsed last, information on anumber of height parsing rows among a plurality of rows for deriving thefirst partitioning structure, whose information on height is parsed, andinformation on a last height indicating a height among the heights ofthe height parsing rows, which is parsed last, deriving a predictedblock for the current block, based on the prediction information for thecurrent block included in one tile of the plurality of tiles, andgenerating reconstructed samples for the current block, based on thepredicted block.

According to another embodiment of this disclosure, a decoding apparatusfor performing image decoding is provided. The decoding apparatusincludes an entropy decoder which receives a bitstream including atleast one of a partition information for a current picture and aprediction information for a current block included in the currentpicture, and derives a first partitioning structure of the currentpicture, based on the partition information for the current picture,wherein the first partitioning structure of the current picture is basedon a plurality of tiles, and wherein the partition information for thecurrent picture includes at least one of information on a number ofwidth parsing columns among a plurality of columns for deriving thefirst partitioning structure, whose information on width is parsed,information on a last width indicating a width among the widths of thewidth parsing columns, which is parsed last, information on a number ofheight parsing rows among a plurality of rows for deriving the firstpartitioning structure, whose information on height is parsed, andinformation on a last height indicating a height among the heights ofthe height parsing rows, which is parsed last, a predictor which derivesa predicted block for the current block, based on the predictioninformation for the current block included in one tile of the pluralityof tiles, and an adder which generates reconstructed samples for thecurrent block, based on the predicted block.

According to still another embodiment of this disclosure, an imageencoding method performed by an encoding apparatus is provided. Themethod includes partitioning a current picture into a plurality oftiles, generating a partition information for the current picture, basedon the plurality of tiles, wherein the partition information for thecurrent picture includes at least one of information on a number ofwidth parsing columns among a plurality of columns for deriving theplurality of tile, whose information on width is parsed, information ona last width indicating a width among the widths of the width parsingcolumns, which is parsed last, information on a number of height parsingrows among a plurality of rows for deriving the plurality of tiles,whose information on height is parsed, and information on a last heightindicating a height among the heights of the height parsing rows, whichis parsed last, deriving a predicted block for a current block includedin one tile of the plurality of tiles, generating a predictioninformation for the current block, based on the predicted block, andencoding image information including at least one of the partitioninformation for the current picture and the prediction information forthe current block.

According to still another embodiment of this disclosure, an encodingapparatus for performing image encoding is provided. The encodingapparatus includes an image partitioner which partitions a currentpicture into a plurality of tiles, and generates a partition informationfor the current picture, based on the plurality of tiles, wherein thepartition information for the current picture includes at least one ofinformation on a number of width parsing columns among a plurality ofcolumns for deriving the plurality of tile, whose information on widthis parsed, information on a last width indicating a width among thewidths of the width parsing columns, which is parsed last, informationon a number of height parsing rows among a plurality of rows forderiving the plurality of tiles, whose information on height is parsed,and information on a last height indicating a height among the heightsof the height parsing rows, which is parsed last, a predictor whichderives a predicted block for a current block included in one tile ofthe plurality of tiles, generates a prediction information for thecurrent block, based on the predicted block, and an entropy encoderwhich encodes image information including at least one of the partitioninformation for the current picture and the prediction information forthe current block.

According to still another embodiment of this disclosure, there isprovided a decoder-readable storage medium which stores information oninstructions that cause a video decoding apparatus to perform decodingmethods according to some embodiments.

According to still another embodiment of this disclosure, there isprovided a decoder-readable storage medium which stores information oninstructions that cause a video decoding apparatus to perform decodingmethod according to an embodiment. The decoding method according to theembodiment includes receiving a bitstream including at least one of apartition information for a current picture and a prediction informationfor a current block included in the current picture, deriving a firstpartitioning structure of the current picture, based on the partitioninformation for the current picture, wherein the first partitioningstructure of the current picture is based on a plurality of tiles, andwherein the partition information for the current picture includes atleast one of information on a number of width parsing columns among aplurality of columns for deriving the first partitioning structure,whose information on width is parsed, information on a last widthindicating a width among the widths of the width parsing columns, whichis parsed last, information on a number of height parsing rows among aplurality of rows for deriving the first partitioning structure, whoseinformation on height is parsed, and information on a last heightindicating a height among the heights of the height parsing rows, whichis parsed last, deriving a predicted block for the current block, basedon the prediction information for the current block included in one tileof the plurality of tiles, and generating reconstructed samples for thecurrent block, based on the predicted block.

According to this disclosure, it is possible to improve overallimage/video compression efficiency.

According to this disclosure, it is possible to increase the efficiencyof picture partitioning.

According to this disclosure, it is possible to increase the efficiencyof picture partitioning, based on the partition information for thecurrent picture.

According to this disclosure, it is possible to improve signalingefficiency for picture partitioning by determining the width (or height)of each of length parsing skip tiles among a plurality of tilesconstituting the current picture, whose information on width and heightis not parsed, based on the last width (or height) among the signaledwidths (or heights).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example of a video/image codingsystem to which the present disclosure may be applied.

FIG. 2 is a diagram schematically illustrating a configuration of avideo/image encoding apparatus to which the present disclosure may beapplied.

FIG. 3 is a diagram for schematically explaining a configuration of avideo/image decoding apparatus to which the present disclosure may beapplied.

FIG. 4 is a flowchart showing a picture encoding procedure based on atile and/or a tile group according to an embodiment.

FIG. 5 is a flowchart showing a picture decoding procedure based on atile and/or a tile group according to an embodiment.

FIG. 6 is a diagram showing an example of partitioning a picture inunits of tiles.

FIG. 7 is a block diagram showing a configuration of an encodingapparatus according to an embodiment.

FIG. 8 is a flowchart showing a configuration of a decoding apparatusaccording to an embodiment.

FIG. 9 is a diagram showing an example of a tile and a tile group unitconstituting a current picture.

FIG. 10 is a diagram schematically showing an example of a signalingstructure of tile group information.

FIG. 11 is a flowchart showing operation of an encoding apparatusaccording to an embodiment.

FIG. 12 is a block diagram showing a configuration of an encodingapparatus according to another embodiment.

FIG. 13 is a flowchart showing operations of a decoding apparatusaccording to an embodiment.

FIG. 14 is a block diagram showing a configuration of a decodingapparatus according to another embodiment.

FIG. 15 represents an example of a content streaming system to which thedisclosure of this document is applicable.

DESCRIPTION OF EMBODIMENTS

According to an embodiment of this disclosure, an image decoding methodperformed by a decoding apparatus is provided. The method includesreceiving a bitstream including at least one of a partition informationfor a current picture and a prediction information for a current blockincluded in the current picture, deriving a first partitioning structureof the current picture, based on the partition information for thecurrent picture, wherein the first partitioning structure of the currentpicture is based on a plurality of tiles, and wherein the partitioninformation for the current picture includes at least one of informationon a number of width parsing columns among a plurality of columns forderiving the first partitioning structure, whose information on width isparsed, information on a last width indicating a width among the widthsof the width parsing columns, which is parsed last, information on anumber of height parsing rows among a plurality of rows for deriving thefirst partitioning structure, whose information on height is parsed, andinformation on a last height indicating a height among the heights ofthe height parsing rows, which is parsed last, deriving a predictedblock for the current block, based on the prediction information for thecurrent block included in one tile of the plurality of tiles, andgenerating reconstructed samples for the current block, based on thepredicted block.

The present disclosure may be modified in various forms, and specificembodiments thereof will be described and illustrated in the drawings.However, the embodiments are not intended for limiting the presentdisclosure. The terms used in the following description are used tomerely describe specific embodiments, but are not intended to limit thepresent disclosure. An expression of a singular number includes anexpression of the plural number, so long as it is clearly readdifferently. The terms such as “include” and “have” are intended toindicate that features, numbers, steps, operations, elements,components, or combinations thereof used in the following descriptionexist and it should be thus understood that the possibility of existenceor addition of one or more different features, numbers, steps,operations, elements, components, or combinations thereof is notexcluded.

In addition, each configuration of the drawings described in the presentdisclosure is an independent illustration for explaining functions asfeatures that are different from each other, and does not mean that eachconfiguration is implemented by mutually different hardware or differentsoftware. For example, two or more of the configurations can be combinedto form one configuration, and one configuration can also be dividedinto multiple configurations. Without departing from the gist of thepresent disclosure, embodiments in which configurations are combinedand/or separated are included in the scope of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. In addition, likereference numerals are used to indicate like elements throughout thedrawings, and the same descriptions on the like elements will beomitted.

FIG. 1 illustrates an example of a video/image coding system to whichthe present disclosure may be applied.

The present disclosure relates to video/image coding. For example, amethod/embodiment disclosed in the present disclosure may be applied toa method disclosed in the versatile video coding (VVC) standard, theessential video coding (EVC) standard, the AOMedia Video 1 (AV1)standard, the 2nd generation of audio video coding standard (AVS2) orthe next generation video/image coding standard (e.g., H.267, H.268, orthe like).

The present disclosure suggests various embodiments of video/imagecoding, and the above embodiments may also be performed in combinationwith each other unless otherwise specified.

In the present disclosure, a video may refer to a series of images overtime. A picture generally refers to the unit representing one image at aparticular time frame, and a slice/tile refers to the unit constitutinga part of the picture in terms of coding. A slice/tile may include oneor more coding tree units (CTUs). One picture may consist of one or moreslices/tiles. One picture may consist of one or more tile groups. Onetile group may include one or more tiles. A brick may represent arectangular region of CTU rows within a tile in a picture (a brick mayrepresent a rectangular region of CTU rows within a tile in a picture).A tile may be partitioned into a multiple bricks, each of which may beconstructed with one or more CTU rows within the tile (A tile may bepartitioned into multiple bricks, each of which consisting of one ormore CTU rows within the tile). A tile that is not partitioned intomultiple bricks may also be referred to as a brick. A brick scan mayrepresent a specific sequential ordering of CTUs partitioning a picture,wherein the CTUs may be ordered in a CTU raster scan within a brick, andbricks within a tile may be ordered consecutively in a raster scan ofthe bricks of the tile, and tiles in a picture may be orderedconsecutively in a raster scan of the tiles of the picture (A brick scanis a specific sequential ordering of CTUs partitioning a picture inwhich the CTUs are ordered consecutively in CTU raster scan in a brick,bricks within a tile are ordered consecutively in a raster scan of thebricks of the tile, and tiles in a picture are ordered consecutively ina raster scan of the tiles of the picture). A tile is a particular tilecolumn and a rectangular region of CTUs within a particular tile column(A tile is a rectangular region of CTUs within a particular tile columnand a particular tile row in a picture). The tile column is arectangular region of CTUs, which has a height equal to the height ofthe picture and a width that may be specified by syntax elements in thepicture parameter set (The tile column is a rectangular region of CTUshaving a height equal to the height of the picture and a width specifiedby syntax elements in the picture parameter set). The tile row is arectangular region of CTUs, which has a width specified by syntaxelements in the picture parameter set and a height that may be equal tothe height of the picture (The tile row is a rectangular region of CTUshaving a height specified by syntax elements in the picture parameterset and a width equal to the width of the picture). A tile scan mayrepresent a specific sequential ordering of CTUs partitioning a picture,and the CTUs may be ordered consecutively in a CTU raster scan in atile, and tiles in a picture may be ordered consecutively in a rasterscan of the tiles of the picture (A tile scan is a specific sequentialordering of CTUs partitioning a picture in which the CTUs are orderedconsecutively in CTU raster scan in a tile whereas tiles in a pictureare ordered consecutively in a raster scan of the tiles of the picture).A slice may include an integer number of bricks of a picture, and theinteger number of bricks may be included in a single NAL unit (A sliceincludes an integer number of bricks of a picture that may beexclusively contained in a single NAL unit). A slice may be constructedwith multiple complete tiles, or may be a consecutive sequence ofcomplete bricks of one tile (A slice may consists of either a number ofcomplete tiles or only a consecutive sequence of complete bricks of onetile). In the present disclosure, a tile group and a slice may be usedin place of each other. For example, in the present disclosure, a tilegroup/tile group header may be referred to as a slice/slice header.

A pixel or a pel may mean a smallest unit constituting one picture (orimage). Also, ‘sample’ may be used as a term corresponding to a pixel. Asample may generally represent a pixel or a value of a pixel, and mayrepresent only a pixel/pixel value of a luma component or only apixel/pixel value of a chroma component.

A unit may represent a basic unit of image processing. The unit mayinclude at least one of a specific region of the picture and informationrelated to the region. One unit may include one luma block and twochroma (ex. cb, cr) blocks. The unit may be used interchangeably withterms such as block or area in some cases. In a general case, an M×Nblock may include samples (or sample arrays) or a set (or array) oftransform coefficients of M columns and N rows.

Referring to FIG. 1, a video/image coding system may include a sourcedevice and a reception device. The source device may transmit encodedvideo/image information or data to the reception device through adigital storage medium or network in the form of a file or streaming.

The source device may include a video source, an encoding apparatus, anda transmitter. The receiving device may include a receiver, a decodingapparatus, and a renderer. The encoding apparatus may be called avideo/image encoding apparatus, and the decoding apparatus may be calleda video/image decoding apparatus. The transmitter may be included in theencoding apparatus. The receiver may be included in the decodingapparatus. The renderer may include a display, and the display may beconfigured as a separate device or an external component.

The video source may acquire video/image through a process of capturing,synthesizing, or generating the video/image. The video source mayinclude a video/image capture device and/or a video/image generatingdevice. The video/image capture device may include, for example, one ormore cameras, video/image archives including previously capturedvideo/images, and the like. The video/image generating device mayinclude, for example, computers, tablets and smartphones, and may(electronically) generate video/images. For example, a virtualvideo/image may be generated through a computer or the like. In thiscase, the video/image capturing process may be replaced by a process ofgenerating related data.

The encoding apparatus may encode input video/image. The encodingapparatus may perform a series of procedures such as prediction,transform, and quantization for compaction and coding efficiency. Theencoded data (encoded video/image information) may be output in the formof a bitstream.

The transmitter may transmit the encoded image/image information or dataoutput in the form of a bitstream to the receiver of the receivingdevice through a digital storage medium or a network in the form of afile or streaming. The digital storage medium may include variousstorage mediums such as USB, SD, CD, DVD, Blu-ray, HDD, SSD, and thelike. The transmitter may include an element for generating a media filethrough a predetermined file format and may include an element fortransmission through a broadcast/communication network. The receiver mayreceive/extract the bitstream and transmit the received bitstream to thedecoding apparatus.

The decoding apparatus may decode the video/image by performing a seriesof procedures such as dequantization, inverse transform, and predictioncorresponding to the operation of the encoding apparatus.

The renderer may render the decoded video/image. The renderedvideo/image may be displayed through the display.

FIG. 2 is a diagram schematically illustrating a configuration of avideo/image encoding apparatus to which the present disclosure may beapplied. Hereinafter, what is referred to as the video encodingapparatus may include an image encoding apparatus.

Referring to FIG. 2, the encoding apparatus 200 may include and beconfigured with an image partitioner 210, a predictor 220, a residualprocessor 230, an entropy encoder 240, an adder 250, a filter 260, and amemory 270. The predictor 220 may include an inter predictor 221 and anintra predictor 222. The residual processor 230 may include atransformer 232, a quantizer 233, a dequantizer 234, and an inversetransformer 235. The residual processor 230 may further include asubtractor 231. The adder 250 may be called a reconstructor orreconstructed block generator. The image partitioner 210, the predictor220, the residual processor 230, the entropy encoder 240, the adder 250,and the filter 260, which have been described above, may be configuredby one or more hardware components (e.g., encoder chipsets orprocessors) according to an embodiment. In addition, the memory 270 mayinclude a decoded picture buffer (DPB), and may also be configured by adigital storage medium. The hardware component may further include thememory 270 as an internal/external component.

The image partitioner 210 may split an input image (or, picture, frame)input to the encoding apparatus 200 into one or more processing units.As an example, the processing unit may be called a coding unit (CU). Inthis case, the coding unit may be recursively split according to aQuad-tree binary-tree ternary-tree (QTBTTT) structure from a coding treeunit (CTU) or the largest coding unit (LCU). For example, one codingunit may be split into a plurality of coding units of a deeper depthbased on a quad-tree structure, a binary-tree structure, and/or aternary-tree structure. In this case, for example, the quad-treestructure is first applied and the binary-tree structure and/or theternary-tree structure may be later applied. Alternatively, thebinary-tree structure may also be first applied. A coding procedureaccording to the present disclosure may be performed based on a finalcoding unit which is not split any more. In this case, based on codingefficiency according to image characteristics or the like, the maximumcoding unit may be directly used as the final coding unit, or asnecessary, the coding unit may be recursively split into coding units ofa deeper depth, such that a coding unit having an optimal size may beused as the final coding unit. Here, the coding procedure may include aprocedure such as prediction, transform, and reconstruction to bedescribed later. As another example, the processing unit may furtherinclude a prediction unit (PU) or a transform unit (TU). In this case,each of the prediction unit and the transform unit may be split orpartitioned from the aforementioned final coding unit. The predictionunit may be a unit of sample prediction, and the transform unit may be aunit for inducing a transform coefficient and/or a unit for inducing aresidual signal from the transform coefficient.

The unit may be interchangeably used with the term such as a block or anarea in some cases. Generally, an M×N block may represent samplescomposed of M columns and N rows or a group of transform coefficients.The sample may generally represent a pixel or a value of the pixel, andmay also represent only the pixel/pixel value of a luma component, andalso represent only the pixel/pixel value of a chroma component. Thesample may be used as the term corresponding to a pixel or a pelconfiguring one picture (or image).

The encoding apparatus 200 may generate a residual signal (residualblock, residual sample array) by subtracting a predicted signal(predicted block, prediction sample array) output from the interpredictor 221 or the intra predictor 222 from the input image signal(original block, original sample array), and the generated residualsignal is transmitted to the transformer 232. In this case, asillustrated, the unit for subtracting the predicted signal (predictedblock, prediction sample array) from the input image signal (originalblock, original sample array) within an encoder 200 may be called thesubtractor 231. The predictor may perform prediction for a block to beprocessed (hereinafter, referred to as a current block), and generate apredicted block including prediction samples of the current block. Thepredictor may determine whether intra prediction is applied or interprediction is applied in units of the current block or the CU. Thepredictor may generate various information about prediction, such asprediction mode information, to transfer the generated information tothe entropy encoder 240 as described later in the description of eachprediction mode. The information about prediction may be encoded by theentropy encoder 240 to be output in a form of the bitstream.

The intra predictor 222 may predict a current block with reference tosamples within a current picture. The referenced samples may be locatedneighboring to the current block, or may also be located away from thecurrent block according to the prediction mode. The prediction modes inthe intra prediction may include a plurality of non-directional modesand a plurality of directional modes. The non-directional mode mayinclude, for example, a DC mode or a planar mode. The directional modemay include, for example, 33 directional prediction modes or 65directional prediction modes according to the fine degree of theprediction direction. However, this is illustrative and the directionalprediction modes which are more or less than the above number may beused according to the setting. The intra predictor 222 may alsodetermine the prediction mode applied to the current block using theprediction mode applied to the neighboring block.

The inter predictor 221 may induce a predicted block of the currentblock based on a reference block (reference sample array) specified by amotion vector on a reference picture. At this time, in order to decreasethe amount of motion information transmitted in the inter predictionmode, the motion information may be predicted in units of a block, asub-block, or a sample based on the correlation of the motioninformation between the neighboring block and the current block. Themotion information may include a motion vector and a reference pictureindex. The motion information may further include inter predictiondirection (L0 prediction, L1 prediction, Bi prediction, or the like)information. In the case of the inter prediction, the neighboring blockmay include a spatial neighboring block existing within the currentpicture and a temporal neighboring block existing in the referencepicture. The reference picture including the reference block and thereference picture including the temporal neighboring block may also bethe same as each other, and may also be different from each other. Thetemporal neighboring block may be called the name such as a collocatedreference block, a collocated CU (colCU), or the like, and the referencepicture including the temporal neighboring block may also be called acollocated picture (colPic). For example, the inter predictor 221 mayconfigure a motion information candidate list based on the neighboringblocks, and generate information indicating what candidate is used toderive the motion vector and/or the reference picture index of thecurrent block. The inter prediction may be performed based on variousprediction modes, and for example, in the case of a skip mode and amerge mode, the inter predictor 221 may use the motion information ofthe neighboring block as the motion information of the current block. Inthe case of the skip mode, the residual signal may not be transmittedunlike the merge mode. A motion vector prediction (MVP) mode mayindicate the motion vector of the current block by using the motionvector of the neighboring block as a motion vector predictor, andsignaling a motion vector difference.

The predictor 200 may generate a predicted signal based on variousprediction methods to be described later. For example, the predictor maynot only apply the intra prediction or the inter prediction forpredicting one block, but also simultaneously apply the intra predictionand the inter prediction. This may be called a combined inter and intraprediction (CIIP). Further, the predictor may be based on an intra blockcopy (IBC) prediction mode, or a palette mode in order to performprediction on a block. The IBC prediction mode or palette mode may beused for content image/video coding of a game or the like, such asscreen content coding (SCC). The IBC basically performs prediction in acurrent picture, but it may be performed similarly to inter predictionin that it derives a reference block in a current picture. That is, theIBC may use at least one of inter prediction techniques described in thepresent document. The palette mode may be regarded as an example ofintra coding or intra prediction. When the palette mode is applied, asample value in a picture may be signaled based on information on apalette index and a palette table.

The predicted signal generated through the predictor (including theinter predictor 221 and/or the intra predictor 222) may be used togenerate a reconstructed signal or used to generate a residual signal.The transformer 232 may generate transform coefficients by applying thetransform technique to the residual signal. For example, the transformtechnique may include at least one of a discrete cosine transform (DCT),a discrete sine transform (DST), a Karhunen-Loeve transform (KLT), agraph-based transform (GBT), or a conditionally non-linear transform(CNT). Here, when the relationship information between pixels isillustrated as a graph, the GBT means the transform obtained from thegraph. The CNT means the transform which is acquired based on apredicted signal generated by using all previously reconstructed pixels.In addition, the transform process may also be applied to a pixel blockhaving the same size of the square, and may also be applied to the blockhaving a variable size rather than the square.

The quantizer 233 may quantize the transform coefficients to transmitthe quantized transform coefficients to the entropy encoder 240, and theentropy encoder 240 may encode the quantized signal (information aboutthe quantized transform coefficients) to the encoded quantized signal tothe bitstream. The information about the quantized transformcoefficients may be called residual information. The quantizer 233 mayrearrange the quantized transform coefficients having a block form in aone-dimensional vector form based on a coefficient scan order, and alsogenerate the information about the quantized transform coefficientsbased on the quantized transform coefficients of the one dimensionalvector form. The entropy encoder 240 may perform various encodingmethods, for example, such as an exponential Golomb coding, acontext-adaptive variable length coding (CAVLC), and a context-adaptivebinary arithmetic coding (CABAC). The entropy encoder 240 may alsoencode information (e.g., values of syntax elements and the like)necessary for reconstructing video/image other than the quantizedtransform coefficients together or separately. The encoded information(e.g., encoded video/image information) may be transmitted or stored inunits of network abstraction layer (NAL) unit in a form of thebitstream. The video/image information may further include informationabout various parameter sets such as an adaptation parameter set (APS),a picture parameter set (PPS), a sequence parameter set (SPS), or avideo parameter set (VPS). In addition, the video/image information mayfurther include general constraint information. The signaled/transmittedinformation and/or syntax elements to be described later in the presentdisclosure may be encoded through the aforementioned encoding procedureand thus included in the bitstream. The bitstream may be transmittedthrough a network, or stored in a digital storage medium. Here, thenetwork may include a broadcasting network and/or a communicationnetwork, or the like, and the digital storage medium may include variousstorage media such as USB, SD, CD, DVD, Blue-ray, HDD, and SSD. Atransmitter (not illustrated) for transmitting the signal output fromthe entropy encoder 240 and/or a storage (not illustrated) for storingthe signal may be configured as the internal/external elements of theencoding apparatus 200, or the transmitter may also be included in theentropy encoder 240.

The quantized transform coefficients output from the quantizer 233 maybe used to generate a predicted signal. For example, the dequantizer 234and the inverse transformer 235 apply dequantization and inversetransform to the quantized transform coefficients, such that theresidual signal (residual block or residual samples) may bereconstructed. The adder 250 adds the reconstructed residual signal tothe predicted signal output from the inter predictor 221 or the intrapredictor 222, such that the reconstructed signal (reconstructedpicture, reconstructed block, reconstructed sample array) may begenerated. As in the case where the skip mode is applied, if there is noresidual for the block to be processed, the predicted block may be usedas the reconstructed block. The adder 250 may be called a reconstructoror a reconstructed block generator. The generated reconstructed signalmay be used for the intra prediction of the next block to be processedwithin the current picture, and as described later, also used for theinter prediction of the next picture through filtering.

Meanwhile, a luma mapping with chroma scaling (LMCS) may also be appliedin a picture encoding and/or reconstruction process.

The filter 260 may apply filtering to the reconstructed signal, therebyimproving subjective/objective image qualities. For example, the filter260 may apply various filtering methods to the reconstructed picture togenerate a modified reconstructed picture, and store the modifiedreconstructed picture in the memory 270, specifically, the DPB of thememory 270. Various filtering methods may include, for example, adeblocking filtering, a sample adaptive offset, an adaptive loop filter,a bilateral filter, and the like. The filter 260 may generate variouskinds of filtering-related information to transfer the generatedinformation to the entropy encoder 240, as described later in thedescription of each filtering method. The filtering-related informationmay be encoded by the entropy encoder 240 to be output in a form of thebitstream.

The modified reconstructed picture transmitted to the memory 270 may beused as the reference picture in the inter predictor 221. If the interprediction is applied by the inter predictor, the encoding apparatus mayavoid the prediction mismatch between the encoding apparatus 200 and thedecoding apparatus, and also improve coding efficiency.

The DPB of the memory 270 may store the modified reconstructed pictureto be used as the reference picture in the inter predictor 221. Thememory 270 may store motion information of the block in which the motioninformation within the current picture is derived (or encoded) and/ormotion information of the blocks within the previously reconstructedpicture. The stored motion information may be transferred to the interpredictor 221 to be utilized as motion information of the spatialneighboring block or motion information of the temporal neighboringblock. The memory 270 may store the reconstructed samples of thereconstructed blocks within the current picture, and transfer thereconstructed samples to the intra predictor 222.

FIG. 3 is a diagram for schematically explaining a configuration of avideo/image decoding apparatus to which the present disclosure isapplicable.

Referring to FIG. 3, the decoding apparatus 300 may include andconfigured with an entropy decoder 310, a residual processor 320, apredictor 330, an adder 340, a filter 350, and a memory 360. Thepredictor 330 may include an inter predictor 331 and an intra predictor332. The residual processor 320 may include a dequantizer 321 and aninverse transformer 322. The entropy decoder 310, the residual processor320, the predictor 330, the adder 340, and the filter 350, which havebeen described above, may be configured by one or more hardwarecomponents (e.g., decoder chipsets or processors) according to anembodiment. Further, the memory 360 may include a decoded picture buffer(DPB), and may be configured by a digital storage medium. The hardwarecomponent may further include the memory 360 as an internal/externalcomponent.

When the bitstream including the video/image information is input, thedecoding apparatus 300 may reconstruct the image in response to aprocess in which the video/image information is processed in theencoding apparatus illustrated in FIG. 2. For example, the decodingapparatus 300 may derive the units/blocks based on block split-relatedinformation acquired from the bitstream. The decoding apparatus 300 mayperform decoding using the processing unit applied to the encodingapparatus. Therefore, the processing unit for the decoding may be, forexample, a coding unit, and the coding unit may be split according tothe quad-tree structure, the binary-tree structure, and/or theternary-tree structure from the coding tree unit or the maximum codingunit. One or more transform units may be derived from the coding unit.In addition, the reconstructed image signal decoded and output throughthe decoding apparatus 300 may be reproduced through a reproducingapparatus.

The decoding apparatus 300 may receive the signal output from theencoding apparatus illustrated in FIG. 2 in a form of the bitstream, andthe received signal may be decoded through the entropy decoder 310. Forexample, the entropy decoder 310 may derive information (e.g.,video/image information) necessary for the image reconstruction (orpicture reconstruction) by parsing the bitstream. The video/imageinformation may further include information about various parameter setssuch as an adaptation parameter set (APS), a picture parameter set(PPS), a sequence parameter set (SPS), and a video parameter set (VPS).In addition, the video/image information may further include generalconstraint information. The decoding apparatus may decode the picturefurther based on the information about the parameter set and/or thegeneral constraint information. The signaled/received information and/orsyntax elements to be described later in the present disclosure may bedecoded through the decoding procedure and acquired from the bitstream.For example, the entropy decoder 310 may decode information within thebitstream based on a coding method such as an exponential Golomb coding,a CAVLC, or a CABAC, and output a value of the syntax element necessaryfor the image reconstruction, and the quantized values of theresidual-related transform coefficient. More specifically, the CABACentropy decoding method may receive a bin corresponding to each syntaxelement from the bitstream, determine a context model using syntaxelement information to be decoded and decoding information of theneighboring block and the block to be decoded or information of thesymbol/bin decoded in the previous stage, and generate a symbolcorresponding to a value of each syntax element by predicting theprobability of generation of the bin according to the determined contextmodel to perform the arithmetic decoding of the bin. At this time, theCABAC entropy decoding method may determine the context model and thenupdate the context model using the information of the decoded symbol/binfor a context model of a next symbol/bin. The information aboutprediction among the information decoded by the entropy decoder 310 maybe provided to the predictor (the inter predictor 332 and the intrapredictor 331), and a residual value at which the entropy decoding isperformed by the entropy decoder 310, that is, the quantized transformcoefficients and the related parameter information may be input to theresidual processor 320. The residual processor 320 may derive a residualsignal (residual block, residual samples, and residual sample array). Inaddition, the information about filtering among the information decodedby the entropy decoder 310 may be provided to the filter 350. Meanwhile,a receiver (not illustrated) for receiving the signal output from theencoding apparatus may be further configured as the internal/externalelement of the decoding apparatus 300, or the receiver may also be acomponent of the entropy decoder 310. Meanwhile, the decoding apparatusaccording to the present disclosure may be called a video/image/picturedecoding apparatus, and the decoding apparatus may also be classifiedinto an information decoder (video/image/picture information decoder)and a sample decoder (video/image/picture sample decoder). Theinformation decoder may include the entropy decoder 310, and the sampledecoder may include at least one of the dequantizer 321, the inversetransformer 322, the adder 340, the filter 350, the memory 360, theinter predictor 332, and the intra predictor 331.

The dequantizer 321 may dequantize the quantized transform coefficientsto output the transform coefficients. The dequantizer 321 may rearrangethe quantized transform coefficients in a two-dimensional block form. Inthis case, the rearrangement may be performed based on a coefficientscan order performed by the encoding apparatus. The dequantizer 321 mayperform dequantization for the quantized transform coefficients using aquantization parameter (e.g., quantization step size information), andacquire the transform coefficients.

The inverse transformer 322 inversely transforms the transformcoefficients to acquire the residual signal (residual block, residualsample array).

The predictor 330 may perform the prediction of the current block, andgenerate a predicted block including the prediction samples of thecurrent block. The predictor may determine whether the intra predictionis applied or the inter prediction is applied to the current block basedon the information about prediction output from the entropy decoder 310,and determine a specific intra/inter prediction mode.

The predictor may generate the predicted signal based on variousprediction methods to be described later. For example, the predictor maynot only apply the intra prediction or the inter prediction for theprediction of one block, but also apply the intra prediction and theinter prediction at the same time. This may be called a combined interand intra prediction (CIIP). Further, the predictor may be based on anintra block copy (IBC) prediction mode, or a palette mode in order toperform prediction on a block. The IBC prediction mode or palette modemay be used for content image/video coding of a game or the like, suchas screen content coding (SCC). The IBC basically performs prediction ina current picture, but it may be performed similarly to inter predictionin that it derives a reference block in a current picture. That is, theIBC may use at least one of inter prediction techniques described in thepresent document. The palette mode may be regarded as an example ofintra coding or intra prediction. When the palette mode is applied,information on a palette table and a palette index may be included inthe video/image information and signaled.

The intra predictor 331 may predict the current block with reference tothe samples within the current picture. The referenced samples may belocated neighboring to the current block according to the predictionmode, or may also be located away from the current block. The predictionmodes in the intra prediction may include a plurality of non-directionalmodes and a plurality of directional modes. The intra predictor 331 mayalso determine the prediction mode applied to the current block usingthe prediction mode applied to the neighboring block.

The inter predictor 332 may induce the predicted block of the currentblock based on the reference block (reference sample array) specified bythe motion vector on the reference picture. At this time, in order todecrease the amount of the motion information transmitted in the interprediction mode, the motion information may be predicted in units of ablock, a sub-block, or a sample based on the correlation of the motioninformation between the neighboring block and the current block. Themotion information may include a motion vector and a reference pictureindex. The motion information may further include inter predictiondirection (L0 prediction, L1 prediction, Bi prediction, or the like)information. In the case of the inter prediction, the neighboring blockmay include a spatial neighboring block existing within the currentpicture and a temporal neighboring block existing in the referencepicture. For example, the inter predictor 332 may configure a motioninformation candidate list based on the neighboring blocks, and derivethe motion vector and/or the reference picture index of the currentblock based on received candidate selection information. The interprediction may be performed based on various prediction modes, and theinformation about the prediction may include information indicating themode of the inter prediction of the current block.

The adder 340 may add the acquired residual signal to the predictedsignal (predicted block, prediction sample array) output from thepredictor (including the inter predictor 332 and/or the intra predictor331) to generate the reconstructed signal (reconstructed picture,reconstructed block, reconstructed sample array). As in the case wherethe skip mode is applied, if there is no residual for the block to beprocessed, the predicted block may be used as the reconstructed block.

The adder 340 may be called a reconstructor or a reconstructed blockgenerator. The generated reconstructed signal may be used for the intraprediction of a next block to be processed within the current picture,and as described later, may also be output through filtering or may alsobe used for the inter prediction of a next picture.

Meanwhile, a luma mapping with chroma scaling (LMCS) may also be appliedin the picture decoding process.

The filter 350 may apply filtering to the reconstructed signal, therebyimproving the subjective/objective image qualities. For example, thefilter 350 may apply various filtering methods to the reconstructedpicture to generate a modified reconstructed picture, and transmit themodified reconstructed picture to the memory 360, specifically, the DPBof the memory 360. Various filtering methods may include, for example, adeblocking filtering, a sample adaptive offset, an adaptive loop filter,a bidirectional filter, and the like.

The (modified) reconstructed picture stored in the DPB of the memory 360may be used as the reference picture in the inter predictor 332. Thememory 360 may store motion information of the block in which the motioninformation within the current picture is derived (decoded) and/ormotion information of the blocks within the previously reconstructedpicture. The stored motion information may be transferred to the interpredictor 260 to be utilized as motion information of the spatialneighboring block or motion information of the temporal neighboringblock. The memory 360 may store the reconstructed samples of thereconstructed blocks within the current picture, and transfer the storedreconstructed samples to the intra predictor 331.

In the present specification, the exemplary embodiments described in thefilter 260, the inter predictor 221, and the intra predictor 222 of theencoding apparatus 200 may be applied equally to or to correspond to thefilter 350, the inter predictor 332, and the intra predictor 331 of thedecoding apparatus 300, respectively.

Meanwhile, as described above, in performing video coding, prediction isperformed to improve compression efficiency. Through this, a predictedblock including prediction samples for a current block as a block to becoded (i.e., a coding target block) may be generated. Here, thepredicted block includes prediction samples in a spatial domain (orpixel domain). The predicted block is derived in the same manner in anencoding apparatus and a decoding apparatus, and the encoding apparatusmay signal information (residual information) on residual between theoriginal block and the predicted block, rather than an original samplevalue of an original block, to the decoding apparatus, therebyincreasing image coding efficiency. The decoding apparatus may derive aresidual block including residual samples based on the residualinformation, add the residual block and the predicted block to generatereconstructed blocks including reconstructed samples, and generate areconstructed picture including the reconstructed blocks.

The residual information may be generated through a transform andquantization procedure. For example, the encoding apparatus may derive aresidual block between the original block and the predicted block,perform a transform procedure on residual samples (residual samplearray) included in the residual block to derive transform coefficients,perform a quantization procedure on the transform coefficients to derivequantized transform coefficients, and signal related residualinformation to the decoding apparatus (through a bit stream). Here, theresidual information may include value information of the quantizedtransform coefficients, location information, a transform technique, atransform kernel, a quantization parameter, and the like. The decodingapparatus may perform dequantization/inverse transform procedure basedon the residual information and derive residual samples (or residualblocks). The decoding apparatus may generate a reconstructed picturebased on the predicted block and the residual block. Also, for referencefor inter prediction of a picture afterward, the encoding apparatus mayalso dequantize/inverse-transform the quantized transform coefficientsto derive a residual block and generate a reconstructed picture basedthereon.

FIG. 4 is a flowchart showing a picture encoding procedure based on atile and/or a tile group according to an embodiment.

In this specification, the term “tile” may refer to a set of CTUs of arectangular region within a specific tile column and a specific tile rowwithin a picture. In an example, a tile may represent a set of bricks ora set of slices.

In this specification, the term “slice” may refer to a set of an integernumber of bricks in a picture included in a single NAL unit. In anexample, a slice may represent a set of tiles.

In this specification, the term “brick” may represent CTU rows of arectangular region included in a tile or slice within a picture.

However, in some embodiments, the meanings of the tile, slice, and brickmay be used interchangeably. Those skilled in the relevant art willunderstand with ease that the tiles, slices, and bricks are used todistinguish units for partitioning a current picture, such as a firstpartition unit, a second partition unit, and a third partition unit,respectively, and that there is no need for them to be interpretedstrictly limited by the definition according to each name.

In an embodiment, picture partitioning (S400) and generation ofinformation about the tile/tile group (S410) may be performed by theimage partitioner 210 of the encoding apparatus, and encoding ofvideo/image information including information on a tile/tile group(S420) may be performed by the entropy encoder 240 of the encodingapparatus.

The encoding apparatus according to an embodiment may perform picturepartitioning for encoding an input picture (S400). The picture mayinclude one or more tiles/tile groups. The encoding apparatus maypartition a picture into various forms under the consideration of imagecharacteristics and coding efficiency of the picture, and may generateinformation indicating a partitioning form having an optimal codingefficiency and signal it to the decoding apparatus.

The encoding apparatus according to an embodiment may determine atile/tile group to be applied to the picture, and may generateinformation on the tile/tile group (S410). The information on thetile/tile group may include information indicating the structure of thetile/tile group for the picture. The information on the tile/tile groupmay be signaled through various parameter sets and/or tile groupheaders, as will be described later. Specific examples will be describedlater.

The encoding apparatus according to an embodiment may encode video/imageinformation including information on the tile/tile group, and may outputthe encoded video/image information in the form of a bitstream (S420).The bitstream may be transferred to the decoding apparatus through adigital storage medium or a network. The video/image information mayinclude HLS and/or tile group header syntax described in this document.In addition, the video/image information may further include theaforementioned prediction information, residual information, (in-loop)filtering information, or the like. For example, the encoding apparatusmay apply in-loop filtering after reconstructing the current picture,encode parameters related to the in-loop filtering, and output theencoded parameters in the form of a bitstream.

Also, the information on the tile/tile group may further includeinformation on a brick, as will be described later.

FIG. 5 is a flowchart showing a picture decoding procedure based on atile and/or a tile group according to an embodiment.

In an embodiment, obtaining information on a tile/tile group from abitstream (S500), deriving a tile/tile group in a picture (S510), andperforming picture decoding based on the tile/tile group (S520) may beperformed by the entropy decoder 310 of the decoding apparatus, andencoding video/image information including information on a tile/tilegroup (S530) may be performed by the sample decoder of the decodingapparatus.

The decoding apparatus according to an embodiment may obtain informationon a tile/tile group from the received bitstream (S500). The informationon the tile/tile group may be obtained through various parameter setsand/or tile group headers, as will be described later. Specific exampleswill be described later. Also, the information on the tile/tile groupmay further include information on a brick, as will be described later.

The decoding apparatus according to an embodiment may derive a tile/tilegroup in the current picture, based on the information on the tile/tilegroup (S510). Also, the decoding apparatus may derive the brick.

The decoding apparatus according to an embodiment may decode the currentpicture, based on the tile/tile group (S520). For example, the decodingapparatus may derives a brick/CTU/CU located in the tile, and performbased on this, inter/intra prediction, residual processing,reconstructed block (picture) generation, and/or in-loop filteringprocedures. Further, in this case, for example, the decoding apparatusmay initialize the context model/information in units of tiles/tilegroups. Also, when the neighboring block or neighboring sample to whichreference is made during inter/intra prediction is located in adifferent tile from the current tile in which the current block islocated, the decoding apparatus may treat the neighboring block orneighboring sample as unavailable.

FIG. 6 is a diagram showing an example of partitioning a picture inunits of tiles.

In this application, a specific term or sentence is used for defining aspecific information or concept. For example, information on the numberof height parsing rows among a plurality of rows for deriving a specificpartitioning structure for partitioning a current picture into aplurality of tiles, whose information on height is parsed is representedas “num_tile_rows_minus1”; information on the number of width parsingrows among a plurality of rows for deriving a specific partitioningstructure for partitioning a current picture into a plurality of tiles,whose information on width is parsed is represented as“num_tile_columns_minus1”; the width among the widths of the widthparsing columns, which is parsed last is represented as “last width”;and the height among the heights of the height parsing columns, which isparsed last is represented as “last height”.

However, “num_tile_rows_minus1” may be replaced with various terms suchas num_exp_tile_rows_minus1, and the like; “num_tile_columns_minus1” maybe replaced with various terms such as num_exp_tile_columns_minus1, andthe like; “last with” may be replaced with last width, LastWidth, andthe like; and “last height” may be replaced with various terms such aslast_height, LastHeight, and the like. Therefore, when interpretingspecific terms or sentences used to define specific information orconcepts herein throughout the description, interpretations limited tothe names should not be made, and the term needs to be interpreted underthe consideration of various operations, functions, and effectsaccording to the contents which the term intends to express.

In an embodiment, tiles may refer to regions within a picture defined bya set of vertical and/or horizontal boundaries that partition thepicture into a plurality of rectangles. FIG. 6 shows an example in whicha picture 600 is partitioned into a plurality of tiles, based on aplurality of column boundaries 610 and row boundaries 620 therein. InFIG. 6, the first 32 largest coding units (or coding tree units (CTUs))are numbered and shown.

In an embodiment, each tile may include an integer number of CTUs whichare processed in a raster scan order within each tile. In this case, aplurality of tiles in the picture, which include the respective tilesmay also be processed in the raster scan order in the picture. The tilesmay be grouped to form tile groups, and tiles within a single tile groupmay be raster scanned. Partitioning a picture into tiles may be definedbased on syntax and semantics of a picture parameter set (PPS).

In an embodiment, information derived from the PPS regarding tiles maybe used to check (or read) the followings. First it may be checkedwhether there is one tile or there is/are one or more tiles in thepicture, and when there is/are one or more tiles, it may be checkedwhether or not the one or more tiles are uniformly distributed, thedimension of the tiles may be checked, and it may be checked whether theloop filter is enabled.

In an embodiment, the PPS may signal the syntax elementsingle_tile_in_pic_flag first. The single_tile_in_pic_flag may indicatewhether there is only one tile in the picture or there are a pluralityof tiles in the picture. When there are a plurality of tiles in thepicture, the decoding apparatus may parse information on the number oftile rows and information on the number of tile columns by using syntaxelements num_tile_columns_minus1 and num_tile_rows_minus1. The syntaxelements num_tile_columns_minus1 and num_tile_rows_minus1 may specify aprocess of partitioning a picture into tile rows and columns. Theheights of the tile rows and the widths of the tile columns may berepresented in terms of CTBs (i.e., in units of CTBs).

In an embodiment, an additional flag may be parsed to check whether ornot tiles in a picture are uniformly spaced. When tiles in the pictureare not uniformly spaced, the number of CTBs per tile for the boundariesof each tile row and column may be explicitly signaled (i.e., the numberof CTBs in each tile row and the number of CTBs in each tile column maybe signaled). If the tiles are uniformly spaced, the tiles may have thesame width and height as each other.

In an embodiment, another flag (e.g., the syntax elementloop_filter_across_tiles_enabled_flag) may be parsed to determinewhether or not a loop filter is enabled for tile boundaries. Table 1below summarizes and shows examples of main information on tiles thatcan be derived by parsing the PPS. Table 1 may represent PPS RBSPsyntax.

TABLE 1 pic_parameter_set_rbsp( ) { Descriptor ... single_tile_in_pic_flag u(1) entropy_coding_sync_enabled_flag u(1) if(!single_tile_in_pic_flag ) { num_tile_columns_minus1 ue(v)num_tile_rows_minus1 ue(v) uniform_spacing_flag u(1) if(!uniform_spacing_flag ) { for( i = 0; i < num_tile_columns_minus1; i++ )column_width_minus1[ i ] ue(v) for( i = 0; i < num_tile_rows_minus1; i++) row_height_minus1[ i ] ue(v) } loop_filter_across_tiles_enabled_ flagu(1) } ... u(1)

Examples of semantics for the syntax elements written in Table 1 may be,for example, as in Table 2 below.

TABLE 2 single_tile_in_pic_flag equal to 1 specifies that there is onlyone tile in each picture referring to the PPS. single_tile_in_pic_flagequal to 0 specifies that there is more than one tile in each picturereferring to the PPS. It is a requirement of bitstream conformance thatthe value of single_tile_in_pic_flag shall be the same for all PPSs thatare activated within a CVS. num_tile_columns_minus1 plus 1 specifies thenumber of tile columns partitioning the picture. num_tile_columns_minus1shall be in the range of 0 to PicWidthInCtbsY − 1, inclusive. When notpresent, the value of num_tile_columns_minus1 is inferred to be equal to0. num_tile_rows_minus1 plus 1 specifies the number of tile rowspartitioning the picture. num_tile_rows_minus1 shall be in the range of0 to PicHeightInCtbsY − 1, inclusive. When not present, the value ofnum_tile_rows_minus1 is inferred to be equal to 0. The variableNumTilesInPic is set equal to ( num_tile_columns_minus1 + 1 ) * (num_tile_rows_minus1 + 1 ). When single_tile_in_pic_flag is equal to 0,NumTilesInPic shall be greater than 1. uniform_tile_spacing_flag equalto 1 specifies that tile column boundaries and likewise tile rowboundaries are distributed uniformly across the picture.uniform_tile_spacing_flag equal to 0 specifies that tile columnboundaries and likewise tile row boundaries are not distributeduniformly across the picture but signalled explicitly using the syntaxelements tile_column_width_minus1[ i ] and tile_row_height_minus1[ i ].When not present, the value of uniform_tile_spacing_flag is inferred tobe equal to 1. tile_column_width_minus1[ i ] plus 1 specifies the widthof the i-th tile column in units of CTBs. tile_row_height_minus1[ i ]plus 1 specifies the height of the i-th tile row in units of CTBs.loop_filter_across_tiles_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across tile boundaries in picturesreferring to the PPS. loop_filter_across_tiles_enabled_flag equal to 0specifies that in-loop filtering operations are not performed acrosstile boundaries in pictures referring to the PPS. The in-loop filteringoperations include the deblocking filter, sample adaptive offset filter,and adaptive loop filter operations. When not present, the value ofloop_filter_across_tiles_enabled_flag is inferred to be equal to 1.

FIG. 7 is a block diagram showing a configuration of an encodingapparatus according to an embodiment, and FIG. 8 is a flowchart showinga configuration of a decoding apparatus according to an embodiment.

FIG. 7 shows an example of a block diagram of an encoding apparatus. Theencoding apparatus 700 shown in FIG. 7 includes a partitioning module710 and an encoding module 720. The partitioning module 710 may performthe same and/or similar operations to those of the image divider 210 ofthe encoding apparatus shown in FIG. 2, and the encoding module 720 mayperform the same and/or similar operations to those of the entropyencoder 240 of the encoding apparatus shown in FIG. 2. The input videomay be partitioned in the partitioning module 710, and then encoded inthe encoding module 720. After being encoded, the encoded video may beoutput from the encoding apparatus 700.

FIG. 8 shows an example of a block diagram of a decoding apparatus. Thedecoding apparatus 800 shown in FIG. 8 includes a decoding module 810and a de-blocking filter 820. The decoding module 810 may perform thesame and/or similar operations to those of the entropy decoder 310 ofthe decoding apparatus shown in FIG. 3, and the de-blocking filter 820may perform the same and/or similar operations to those of the filter350 of the decoding apparatus shown in FIG. 3. The decoding module 810may decode the input received from the encoding apparatus 700, andderive information on tiles. A processing unit may be determined basedon the decoded information, and the de-blocking filter 820 may processthe processing unit by applying an in-loop de-blocking filter. In-loopfiltering may be applied to remove coding artifacts generated in thepartitioning process. The in-loop filtering operation may include anadaptive loop filter (ALF), a de-blocking filter (DF), a sample adaptiveoffset (SAO), and the like. Thereafter, the decoded picture may beoutput.

An example of a descriptor specifying the parsing process of each syntaxelement is shown in Table 3 below.

TABLE 3 ae(v): context-adaptive arithmetic entropy-coded syntax element.b(8): byte having any pattern of bit string (8 bits). The parsingprocess for this descriptor is specified by the return value of thefunction read_bits( 8 ). f(n): fixed-pattern bit string using n bitswritten (from left to right) with the left bit first. The parsingprocess for this descriptor is specified by the return value of thefunction read_bits( n ). i(n): signed integer using n bits. When n is“v” in the syntax table, the number of bits varies in a manner dependenton the value of other syntax elements. The parsing process for thisdescriptor is specified by the return value of the function read_bits( n) interpreted as a two's complement integer representation with mostsignificant bit written first. se(v): signed integer 0-th orderExp-Golomb-coded syntax element with the left bit first. The parsingprocess for this descriptor is specified with the order k equal to 0.st(v): null-terminated string encoded as universal coded character set(UCS) transmission format-8 (UTF-8) characters as specified in ISO/IEC10646. The parsing process is specified as follows: st(v) begins at abyte-aligned position in the bitstream and reads and returns a series ofbytes from the bitstream, beginning at the current position andcontinuing up to but not including the next byte-aligned byte that isequal to 0x00, and advances the bitstream pointer by ( stringLength + 1) * 8 bit positions, where stringLength is equal to the number of bytesreturned. NOTE - The st(v) syntax descriptor is only used in thisSpecification when the current position in the bitstream is abyte-aligned position.ib(v): truncated binary using up to maxVal bitswith maxVal defined in the semantics of the symtax element. tu(v):truncated unary using up to maxVal bits with maxVal defined in thesemantics of the symtax element. u(n): unsigned integer using n bits.When n is “v” in the syntax table, the number of bits varies in a mannerdependent on the value of other syntax elements. The parsing process forthis descriptor is specified by the return value of the functionread_bits( n ) interpreted as a binary representation of an unsignedinteger with most significant bit written first. ue(v): unsigned integer0-th order Exp-Golomb-coded syntax element with the left bit first. Theparsing process for this descriptor is specified with the order k equalto 0. uek(v): unsigned integer k-th older Exp-Golomb-coded syntaxelement with the left bit first. The parsing process for this descriptoris specified with the order k defined in the semantics of the symtaxelement.

FIG. 9 is a diagram showing an example of a tile and a tile group unitconstituting a current picture.

As described above, tiles may be grouped to form tile groups. FIG. 9shows an example in which one picture is partitioned into tiles and tilegroups. In FIG. 9, the picture includes 9 tiles and 3 tile groups. Eachof the tile groups may be independently coded.

FIG. 10 is a diagram schematically showing an example of a signalingstructure of tile group information.

Each of the tile groups may include a tile group header in a Coded VideoSequence (CVS). Tile groups may represent a meaning similar to that of aslice group. Each of the tile groups may be independently coded. A tilegroup may include one or more tiles. The tile group header may makereference to a PPS, and subsequently, the PPS may make reference to asequence parameter set (SPS).

In FIG. 10, the tile group header may have a PPS index of the PPS towhich the tile group header makes reference. Subsequently, the PPS maymake reference to the SPS.

In addition to the PPS index, the tile group header according to anembodiment may be determined for the following information. First, ifthere are more than one tiles per picture, the tile group address andthe number of the tiles in the tile group may be determined. Next, atile group type may be determined as intra/predictive/bi-directional.Then, a Picture Order Count (POC) of Lease Significant Bits (LSBs) maybe determined. Next, if there are more than one tiles in one picture,the offset length and entry point to the tile may be determined.

Table 4 below shows an example of syntax of a tile group header.

TABLE 4 tile_group_header( ) { Descriptortile_group_pic_parameter_set_id ue(v) if( NumTilesInPic > 1 ) {tile_group_address u(v) num_tiles_in_tile_group_minus1 ue(v) }tile_group_type ue(v) tile_group_pic_order_cnt_lsb u(v) if(partition_constraints_override_enabled_flag ) {partition_constraints_override_flag ue(v) ... if(num_tiles_in_tile_group_minus1 > 0 ) { offset_len_minus1 ue(v) for( i =0; i < num_tiles_in_tile_group_minus1; i++ ) entry_point_offset_minus1[i ] u(v) } byte_alignment( ) }

The following shows an example of English semantics for the syntax ofthe tile group header.

<English Semantics for Syntax of Tile Group Header>

When present, the value of the tile group header syntax elementtile_group_pic_parameter_set_id and tile_group_pic_order_cnt_lsb shallbe the same in all tile group headers of a coded picture.

tile_group_pic_parameter_set_id specifies the value ofpps_pic_parameter_set_id for the PPS in use. The value oftile_group_pic_parameter_set_id shall be in the range of 0 to 63,inclusive.

It is a requirement of bitstream conformance that the value of TemporaIdof the current picture shall be greater than or equal to the value ofTemporaId of the PPS that has pps_pic_parameter_set_id equal totile_group_pic_parameter_set_id.

tile_group_address specifies the tile address of the first tile in thetile group, where tile address is the tile ID. The length oftile_group_address is Ceil(Log 2 (NumTilesInPic)) bits. The value oftile_group_address shall be in the range of 0 to NumTilesInPic−1,inclusive, and the value of tile_group_address shall not be equal to thevalue of tile_group_address of any other coded tile group NAL unit ofthe same coded picture. When tile_group_address is not present it isinferred to be equal to 0.

num_tiles_in_tile_group_minus1 plus 1 specifies the number of tiles inthe tile group. The value of num_tiles_in_tile_group_minus1 shall be inthe range of 0 to NumTilesInPic−1, inclusive. When not present, thevalue of num_tiles_in_tile_group_minus1 is inferred to be equal to 0.

tilegroup_type specifies the coding type of the tile group according toTable 5.

TABLE 5 tile_group_type Name of tile_group_type 0 B (B tile group) 1 P(P tile group) 2 I (I tile group)

When nal_unit_type is equal to IRAP_NUT, i.e., the picture is an IRAPpicture, tilegroup_type shall be equal to 2.

tile_group_pic_order_cnt_lsb specifies the picture order count moduloMaxPicOrderCntLsb for the current picture. The length of thetile_group_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4+4 bits. The value of thetile_group_pic_order_cnt_lsb shall be in the range of 0 toMaxPicOrderCntLsb−1, inclusive.

offset_len_minus1 plus 1 specifies the length, in bits, of theentry_point_offset_minus1[i] syntax elements. The value ofoffset_len_minus1 shall be in the range of 0 to 31, inclusive.

entry_point_offset_minus1[i] plus 1 specifies the i-th entry pointoffset in bytes, and is represented by offset_len_minus1 plus 1 bits.The tile group data that follow the tile group header consists ofnum_tiles_in_tile_group_minus1+1 subsets, with subset index valuesranging from 0 to num_tiles_in_tile_group_minus1, inclusive. The firstbyte of the tile group data is considered byte 0. When present,emulation prevention bytes that appear in the tile group data portion ofthe coded tile group NAL unit are counted as part of the tile group datafor purposes of subset identification. Subset 0 consists of bytes 0 toentry_point_offset_minus1[0], inclusive, of the coded tile group data,subset k, with k in the range of 1 to num_tiles_in_tile_group_minus1−1,inclusive, consists of bytes firstByte[k] to lastByte[k], inclusive, ofthe coded tile group data with firstByte[k] and lastByte[k] defined as:

${{firstByte}\lbrack k\rbrack} = {\sum\limits_{n = 1}^{k}\left( {{{entry\_ point}{\_ offset}\_{1\left\lbrack {n - 1} \right\rbrack}} + 1} \right)}$lastByte[k] = firstByte[k] + entry_point_offset_minus1[k]

The last subset (with subset index equal tonum_tiles_in_tile_group_minus1) consists of the remaining bytes of thecoded tile group data.

Each subset shall consist of all coded bits of all CTUs in the tilegroup that are within the same tile.

In an embodiment, the tile group may include a tile group header andtile group data. When the tile group address is known, individualpositions of respective CTUs in the tile group may be mapped anddecoded. Table 6 below shows an example of syntax of tile group data.

TABLE 6 tile_group_data( ) { Descriptor tileIdx = tile_group_addressfor( i = 0: i <= num_tiles_in_tile_group_minus1: i++, tileIdx++ ) {ctbAddrInTs = FirstCtbAddrTs[ tileIdx ] for( j = 0: j < NumCtusInTile[tileIdx ]; j++, ctbAddrInTs++ ) { CtbAddrInRs = CtbAddrTsToRs[ctbAddrInTs ] coding_tree_unit ( ) } end_of_tile_one_bit/* equal to 1 */ ae(v) if( i < num_tiles_in_tile_group_minus1 ) byte_alignment( ) } }

The following shows an example of English semantics for the syntax ofthe tile group data.

<English Semantics for Syntax of Tile Group Data>

Where the semantics are:

The list ColWidth[i] for i ranging from 0 to num_tile_columns_minus1,inclusive, specifying the width of the i-th tile column in units ofCTBs, is derived as follows:

  if( uniform_tile_spacing_flag ) for( i = 0; i <=num_tile_columns_minus1; i++ ) ColWidth[ i ] = ( ( i + 1) *PicWidthInCtbsY ) / ( num_tile_columns_minus1 + 1) − ( i *PicWidthInCtbsY ) / ( num_tile_columns_minus1 + 1 ) else { ColWidth[num_tile_columns_minus1 ] = PicWidthInCtbsY for( i = 0; i <num_tile_columns_minus1; i++ ) { ColWidth[ i ] =tile_column_width_minus1[ i ] + 1 ColWidth[ num_tile_columns_minus1 ] −=ColWidth[ i ] } }

The list RowHeight[j] for j ranging from 0 to num_tile_rows_minus1,inclusive, specifying the height of the j-th tile row in units of CTBs,is derived as follows:

  if( uniform_tile_spacing_flag ) for( j = 0; j <= num_tile_rows_minus1;j++ ) RowHeight[ j ] = ( ( j + 1) * PicHeightInCtbsY ) / (num_tile_rows_minus1 + 1) − ( j * PicHeightInCtbsY ) / (num_tile_rows_minus1 + 1) else { RowHeight[ num_tile_rows_minus1 ] =PicHeightInCtbsY for( j = 0; j < num_tile_rows_minus1; j++ ) {RowHeight[ j ] = tile_row_height_minus1[ j ] + 1 RowHeight[num_tile_rows_minus1 ] = RowHeight[ j ] } }

The list ColBd[i] for i ranging from 0 to num_tile_columns_minus1+1,inclusive, specifying the location of the i-th tile column boundary inunits of CTBs, is derived as follows:

for( ColBd[ 0 ] = 0, i = 0; i <= num_tile_columns_minus1; i++ ) ColBd[i + 1 ] = ColBd[ i ] + ColWidth[ i ]

The list RowBd[j] for j ranging from 0 to num_tile_rows_minus1+1,inclusive, specifying the location of the j-th tile row boundary inunits of CTBs, is derived as follows:

for( RowBd[ 0 ] = 0, j = 0; j <= num_tile_rows_minus1; j++ ) RowBd[ j +1 ] = RowBd[ j ] + RowHeight[ j ]

The list CtbAddrRsToTs[ctbAddrRs] for ctbAddrRs ranging from 0 toPicSizeInCtbsY−1, inclusive, specifying the conversion from a CTBaddress in CTB raster scan of a picture to a CTB address in tile scan,is derived as follows:

  for( ctbAddrRs = 0; ctbAddrRs < PicSizeInCtbsY; ctbAddrRs++ ) { tbX =ctbAddrRs % PicWidthInCtbsY tbY = ctbAddrRs / PicWidthInCtbsY for( i =0; i <= num_tile_columns_minus1; i++ ) if( tbX >= ColBd[ i ] ) tileX = ifor( j = 0; j <= num_tile_rows_minus1; j++ ) if( tbY >= RowBd[ j ] )tileY = j CtbAddrRsToTs[ ctbAddrRs ] = 0 for( i = 0; i < tileX; i++ )CtbAddrRsToTs[ ctbAddrRs ] += RowHeight[ tileY ] * ColWidth[ i ] for( j= 0; j < tileY; j++ ) CtbAddrRsToTs[ ctbAddrRs ] += PicWidthInCtbsY *RowHeight[ j ] CtbAddrRsToTs[ ctbAddrRs ] += ( tbY RowBd+ tileY I) *ColWidth[ tileX ] + tbX − ColBd[ tileX ] }

The list CtbAddrTsToRs[ctbAddrTs] for ctbAddrTs ranging from 0 toPicSizeInCtbsY−1, inclusive, specifying the conversion from a CTBaddress in tile scan to a CTB address in CTB raster scan of a picture,is derived as follows:

for( ctbAddrRs = 0; ctbAddrRs < PicSizeInCtbsY; ctbAddrRs++ )CtbAddrTsToRs[ CtbAddrRsToTs[ ctbAddrRs ] ] = ctbAddrRs

The list TileId[ctbAddrTs] for ctbAddrTs ranging from 0 toPicSizeInCtbsY−1, inclusive, specifying the conversion from a CTBaddress in tile scan to a tile ID, is derived as follows:

for( j = 0, tileIdx = 0; j <= num_tile_rows_minus1; j++ ) for( i = 0; i<= num_tile_columns_minus1; i++ , tileIdx++ ) for( y = RowBd[ j ]; y <RowBd[ j + 1 ]; y++ ) for( x = ColBd[ i ]; x < ColBd[ i + 1]; x++ )TileId[ CtbAddrRsToTs[ y * PicWidthInCtbsY+ x ] ] = tileIdx

The list NumCtusInTile[tileIdx] for tileIdx ranging from 0 toPicSizeInCtbsY−1, inclusive, specifying the conversion from a tile indexto the number of CTUs in the tile, is derived as follows:

for( j = 0, tileIdx = 0; j <= num_tile_rows_minus1; j++ ) for( i = 0; i<= num_tile_columns_minus1; i++ , tileIdx++ ) NumCtusInTile[ tileIdx ] =ColWidth[ i ] * RowHeight[ j ]

The list FirstCtbAddrTs[tileIdx] for tileIdx ranging from 0 toNumTilesInPic−1, inclusive, specifying the conversion from a tile ID tothe CTB address in tile scan of the first CTB in the tile are derived asfollows:

for( ctbAddrTs = 0, tileIdx = 0, tileStartFlag = 1; ctbAddrTs <PicSizeInCtbsY; ctbAddrTs++ ) { if( tileStartFlag) { FirstCtbAddrTs[tileIdx ] = ctbAddrTs tileStartFlag = 0 } tileEndFlag = ctbAddrTs = =PicSizeInCtbsY − 1 | | TileId[ ctbAddrTs + 1] ! = TileId[ ctbAddrTs ]if( tileEndFlag ) { tileIdx++ tileStartFlag = 1 } }

The values of ColumnWidthInLumaSamples[i], specifying the width of thei-th tile column in units of luma samples, are set equal toColWidth[i]<<CtbLog 2 SizeY for i ranging from 0 tonum_tile_columns_minus1, inclusive.

The values of RowHeightInLumaSamples[j], specifying the height of thej-th tile row in units of luma samples, are set equal toRowHeight[j]<<<CtbLog 2 SizeY for j ranging from 0 tonum_tile_rows_minus1, inclusive.

In an embodiment, in relation to a use case and application of tiles,there may be various application examples requiring partition of apicture.

In an example, parallel processing will be discussed. Implementationsexecuted on multi-core CPUs may require that a source picture bepartitioned into tiles and tile groups. Each tile group may be processedin parallel on a separate core. The parallel processing may bebeneficial to high-resolution real-time encoding of videos.Additionally, the parallel processing may reduce information sharingbetween tile groups, thereby reducing memory constraints. Since tilesmay be distributed to different threads during parallel processing,parallel architecture may benefit from this partitioning mechanism.

In another example, a maximum transmission unit (MTU) size matching willbe discussed. The coded pictures transmitted through the network may besubjected to fragmentation when the coded pictures are larger than theMTU size. Similarly, if the coded segments are small, the InternetProtocol (IP) header may become important. The packet fragmentation mayresult in loss of error resiliency. Partitioning the picture into tilesand packing each tile/tile group into a separate packet to mitigate theeffects of the packet fragmentation may ensure that the packet issmaller than the MTU size.

In another example, the error resilience will be discussed. Errorresilience may be motivated by requirements of some applications toapply Unequal Error Protection (UEP) to coded tile groups.

In an embodiment, explicit uniform signaling for picture partitioningmay be proposed. In other words, explicit signaling of information ontile columns and tile rows for uniform spacing may be proposed. Table 7below shows an example which is partially extracted syntax of the PPSlevel, and Table below shows an example of semantics for the partiallyextracted syntax.

TABLE 7 pic_parameter_set_rbsp( ) { Descriptor ...single_tile_in_pic_flag  u(1) if( !single_tile_in_pic_flag ) {uniform_tile_spacing_flag  u(1) if( uniform_tile_spacing_flag ) {tile_cols_width_minus1  ue(v) tile_rows_height_minus1  ue(v) } else {num_tile_columns_minus1  ue(v) num_tile_rows_minus1  ue(v) for( i = 0; i< num_tile_columns_minus1; i++ ) tile_column_width_minus1[ i ]  ue(v)for( i = 0; i < num_tile_rows_minus1; i++ ) tile_row_height_minus1[ i ] ue(v) } ...

TABLE 8 single_tile_in_pic_flag equal to 1 specifies that there is onlyone tile in each picture referring to the PPS. single_tile_in_pic_flagequal to 0 specifies that there is more than one tile in each picturereferring to the PPS. NOTE - In absence of further brick splittingwithin a tile, the whole tile is referred to as a brick. When a picturecontains only a single tile without further brick splitting, it isreferred to as a single brick. It is a requirement of bitstreamconformance that the value of single_tile_in_pic_flag shall be the samefor all PPSs that are activated within a CVS. uniform_tile_spacing_flagequal to 1 specifies that tile column boundaries and likewise tile rowboundaries are distributed uniformly across the picture and signalledusing the syntax elements tile_cols_width_minus1 andtile_rows_height_minus1. uniform_tile_spacing_flag equal to 0 specifiesthat tile column boundaries and likewise tile row boundaries may or maynot be distributed uniformly across the picture and signalled using thesyntax elements num_tile_columns_minus1 and num_tile_rows_minus1 and alist of syntax element pairs tile_column_width_minus1[ i ] andtile_row_height_minus1[ i ]. When not present, the value ofuniform_tile_spacing_flag is inferred to be equal to 1.tile_cols_width_minus1 plus 1 specifies the width of the tile columnsexcluding the right-most tile column of the picture in units of CTBswhen uniform_tile_spacing_flag is equal to 1. The value oftile_cols_width_minus1 shall be in the range of 0 to PicWidthInCtbsY −1, inclusive. tile_rows_height_minus1 plus 1 specifics the height of thetile rows excluding the bottom tile row of the picture in units of CTBswhen uniform_tile_spacing_flag is equal to 1. The value oftile_rows_height_minus1 shall be in the range of 0 to PicHeightInCtbsY −1, inclusive. num_tile_columns_minus1 plus 1 specifies the number oftile columns partitioning the picture when uniform_tile_spacing_flag isequal to 0. The value of num_tile_columns_minus1 shall be in the rangeof 0 to PicWidthInCtbsY − 1, inclusive. If single_tile_in_pic_flag isequal to 1, the value of num_tile_columns_minus1 is inferred to be equalto 0. Otherwise, when uniform_tile_spacing_flag is equal to 1, the valueof num_tile_columns_minus1 is inferred. num_tile_rows_minus1 plus 1specifies the number of tile rows partitioning the picture whenuniform_tile_spacing_flag is equal to 0. The value ofnum_tile_rows_minus1 shall be in the range of 0 to PicHeightInCtbsY − 1,inclusive. If single_tile_in_pic_flag is equal to 1, the value ofnum_tile_rows_minus1 is inferred to be equal to 0. Otherwise, whenuniform_tile_spacing_flag is equal to 1, the value ofnum_tile_rows_minus1 is inferred. The variable NumTilesInPic is setequal to ( num_tile_columns_minus1 + 1 ) * ( num_tile_rows_minus1 + 1).When single_tile_in_pic_flag is equal to 0, NumTilesInPic shall begreater than 1. tile_column_width_minus1[ i ] plus 1 specifies the widthof the i-th tile column in units of CTBs. tile_row_height_minus1[ i ]plus 1 specifies the height of the i-th tile row in units of CTBs.

In an embodiment, when there are a plurality of tiles in a picture, asyntax element uniform_tile_spacing_flag indicating whether or not toderive tiles having the same width and height by uniformly partitioningthe picture may be parsed. The syntax element uniform_tile_spacing_flagmay be used when indicating whether or not tiles in a picture areuniformly partitioned. When the syntax element uniform_tile_spacing_flagis enabled, the width of the tile column and the height of the tile rowmay be explicitly parsed. That is, the syntax elementtile_cols_width_minus1 indicating the width of the tile column and thesyntax element tile_rows_height_minus1 indicating the height of the tilerow may be explicitly signaled and/or parsed.

In addition, the syntax elements num_tile_columns_minus1 andnum_tile_rows_minus1 may be signaled and/or parsed. The syntax elementnum_tile_columns_minus1 may indicate the number of explicitly signaledtile columns when partitioning a picture into a plurality of tiles,based on explicitly signaled widths of tile columns. Alternatively, thesyntax element num_tile_columns_minus1 may indicate the number ofexplicitly signaled tile columns, when partitioning a partial region ina picture into a plurality of tiles, based on the explicitly signaledwidths of tile columns for the partial region. When the syntax elementnum_tile_columns_minus1 indicates the number of tile columns whosewidths are signaled to partition a partial region in a picture into aplurality of tiles, the syntax element num_tile_columns_minus1 may beexpressed as a syntax element num_exp_tile_columns_minus1.

Similarly, the syntax element num_tile_rows_minus1 may indicate thenumber of explicitly signaled tile rows, when partitioning a pictureinto a plurality of tiles, based on explicitly signaled heights of tilerows. Alternatively, the syntax element num_tile_rows_minus1 mayindicate the number of explicitly signaled tile rows, when partitioninga partial region in a picture into a plurality of tiles, based on theexplicitly signaled heights of tile rows for the partial region. Whenthe syntax element num_tile_rows_minus1 indicates the number of tilecolumns whose heights are signaled to partition a partial region in apicture into a plurality of tiles, the syntax elementnum_tile_rows_minus1 may be expressed as a syntax elementnum_exp_tile_rows_minus1.

In an embodiment, said num_exp_tile_columns_minus1 (ornum_tile_columns_minus1) may represent an example of information on thenumber of width parsing columns among a plurality of tile columns forderiving a tile partitioning structure in the current picture, whoseinformation on width is parsed, and said num_exp_tile_rows_minus1(ornum_tile_rows_minus1) may represent an example of information on thenumber of height parsing rows among a plurality of rows for deriving atile partition structure in the current picture, whose information onheight is parsed. Information on the last width indicating a width amongthe widths of the width parsing columns, which is parsed last may beexpressed as tile_column_width_minus1 [num_exp_tile_columns_minus1]+1 ortile_column_width_minus1 [num_tile_columns_minus1]+1 based on Table 6.Information on the last height indicating a height among the heights ofthe height-parsed rows, which is parsed last may be expressed astile_row_height_minus1 [num_exp_tile_rows_minus1]+1 ortile_row_height_minus1 [num_tile_rows_minus1]+1 based on Table 6 above.

In an example, all the widths of the width parsing skip columns amongthe plurality of columns, whose information on the width is not parsedmay be determined by the last width (e.g., said tile_column_width_minus1[num_exp_tile_columns_minus1]+1 or tile_column_width_minus1[num_tile_columns_minus1]+1), and all the heights of the height parsingskip rows among the plurality of rows, whose information on the heightis not parsed may be determined by the last height (e.g., saidtile_row_height_minus1 [num_exp_tile_rows_minus1]+1 ortile_row_height_minus1 [num_tile_rows_minus1]+1). More specifically,uniform spacing may be applied to widths of the width parsing skipcolumns and heights of the height parsing skip rows. In other words,without parsing uniform_tile_spacing_flag for determining whether or notto set tile spacing uniformly, a tile partitioning structure may bederived based on uniform spacing in some or all regions in the currentpicture. Those skilled in the relevant art may easily derive Table 9,Equation 1, and Equation 2 below from Table 7, based on this example.

TABLE 9 pic_parameter_set_rbsp( ) { Descriptor ... no_pic_partition_flag u(1) if( !no_pic_partition_flag ) { pps_log2_ctu_size_minus5  u(2)num_exp_tile_columns_minus1  ue(v) num_exp_tile_rows_minus1  ue(v) for(i = 0; i <= num_exp_tile_columns_minus1; i++ ) tile_column_width_minus[i ]  ue(v) for( i = 0; i <= num_exp_tile_rows_minus1; i++ )tile_row_height_minus1[ i ]  ue(v)

[Equation 1]  remainingWidthInCtbsY = PicWidthInCtbsY  for( i = 0; i <num_exp_tile_columns_minus1; i++) {   colWidth[ i ] =tile_column_width_minus1[ i ] + 1   remainingWidthInCtbsY −= colWidth[ i]  }  uniformTileColWidth = tile_column_width_minus1[num_exp_tile_columns_minus1 ] + 1  while( remainingWidthInCtbsY >=uniformTileColWidth ) {   colWidth[ i++ ] = uniformTileColWidth  remainingWidthInCtbsY −= uniformTileColWidth  }  if(remainingWidthInCtbsY >0 )   colWidth[ i++ ] = remainingWidthInCtbsY NumTileColumns = i

  [Equation 2]  remainingHeightInCtbsY = PicHeightInCtbsY  for( j = 0; j< num_exp_tile_rows_minus1; j++) {   RowHeight[ j ] =tile_row_height_minus1[ j ] + 1   remainingHeightInCtbsY −= RowHeight[ j]  }  uniformTileRowHeight = tile_row_height_minus1[num_exp_tile_rows_minus1 ] + 1  while( remainingHeightInCtbsY >=uniformTileRowHeight ) {   RowHeight[ j++ ] = uniformTileRowHeight  remainingHeightInCtbsY −= uniformTileRowHeight  }  if(remainingHeightInCtbsY >0 )   RowHeight[ j++ ] = remainingHeightInCtbsY NumTileColumns = j

Referring to Table 9, num_exp_tile_columns_minus1 indicating the numberof width parsing columns and num_exp_tile_rows_minus1 indicating thenumber of height parsing rows are parsed at the PPS level, and thereby,it may be confirmed thattile_column_width_minus1[num_exp_tile_columns_minus1] indicating thelast width and tile_row_height_minus1[num_exp_tile_rows_minus1]indicating the last height are parsed. Referring to Equation 1, it maybe confirmed that tile_column_width_minus1[num_exp_tile_columns_minus1]indicating the last width indicates the width of the uniform tile column(uniformTileColWidth), and referring to Equation 2, it may be confirmedthat tile_row_height_minus1[num_exp_tile_rows_minus1] indicating thelast height indicates the height of the uniform tile row(uniformTileRowHeight).

In an embodiment, after the process of partitioning the picture intotiles is performed, the process of partitioning the picture into bricksmay be performed. First, a brick partitioning process may be startedbased on brick_splitting_present_flag indicating whether or not one ormore tiles of pictures making reference to the PPS can be partition intotwo or more bricks. Next, for each tile in the picture, a flagindicating whether or not the tile can be partitioned into bricks may beparsed. If a tile can be partitioned into bricks, it may be determinedwhether or not the tile can be divided uniformly. Ifuniform_brick_spacking_flag can be parsed anduniform_brick_spacking_flag is enabled, then the height of a brick's rowmay be explicitly parsed. If the tiles are not uniformly partitioned,the height of each brick row may be parsed for each brick.

Additionally, single_brick_per_slice_flag may be parsed.single_brick_per_slice_flag may indicate whether or not each slicemaking reference to the PPS includes one brick. If each slice does notinclude one brick, a rectangular slice flag may be parsed. If the valueof rect_slice_flag is 1 (or true) and there are a plurality of bricks inone slice, then num_slices_in_pic_minus1 indicating the number of slicesin the picture may be parsed. Next, for each slice in the picture, adelta corresponding to the difference between the index of the top-leftbrick and the index number may be parsed.

An example of a syntax representing the brick structure may be as inTable 10 below, and an example of semantics for a syntax representingthe brick structure may be as in Table 11 below.

TABLE 10 pic_parameter_set_rbsb( ) { Descriptor pps_pic_parameter_set_id ue(v) pps_seq_parameter_set_id  ue(v) single_tile_in_pic_flag  u(1) if(!single tile in pic flag ) { uniform_tile_spacing_flag  u(1) if(uniform_tile_spacing_flag ) { tile_cols_width_minus1  ue(v)tile_rows_height_minus1  ue(v) } else { num_tile_columns_minus1  ue(v)num_tile_rows_minus1  ue(v) for( i = 0; i < num_tile_columns_minus1; i++) tile_column_width_minus1[ i ]  ue(v) for( i = 0; i <num_tile_rows_minus1; i++ ) tile_row_height_minus1[ i ]  ue(v) }brick_splitting_present_flag  u(1) for( i = 0; brick_present_flag && i <NumTilesInPic; i ++ ) { brick_split_flag[ i ]  u(1) if(brick_split_flag[ i ] ) { uniform_brick_spacing_flag[ i ]  u(1) if(uniform_brick_spacing_flag[ i ]) brick_rows_height_minus1[ i ]  ue(v)else { num_brick_rows_minus1[ i ]  ue(v) for( j = 0; j <num_brick_rows_minus1[ i ]; j++ ) brick_row_height_minus1[ i ][ j ] ue(v) } } } single_brick_per_slice_flag  u(1) if(!single_brick_per_slice_flag ) rect_slice_flag  u(1) if( rect_slice_flag&&!single_brick_per_slice_flag ) { num_slices_in_pic_minus1  ue(v) for(i = 0; i <= num_slices_in_pic_minus1; i++ ) { if( i > 0 )top_left_brick_idx[ i ]  u(v) bottom_right_brick_idx[ i ]  u(v) } }loop_filter_across_bricks_enabled_flag  u(1) if(loop_filter_across_bricks_enabled_flag )loop_filter_across_slices_enabled_flag  u(1) } if( rect_slice_flag ) {signalled_slice_id_flag  u(1) if( signalled_slice_id_flag ) {signalled_slice_id_length_minus1  ue(v) for( i = 0; i <=num_slices_in_pic_minus1; i++ ) slice_id[ i ]  u(v) } } ... }

TABLE 11 brick_splitting_present_flag equal to 1 specifies that one ormore tiles of pictures referring to the PPS may be divided into two ormore bricks. brick_splitting_present_flag equal to 0 specifies that notiles of pictures referring to the PPS are divided into two of morebricks. brick_split_flag[ i ] equal to 1 specifies that the i-th tile isdivided into two or more bricks. brick_split_flag[ i ] equal to 0specifies that the i-th tile is not divided into two or more bricks.When not present, the value of brick_split_flag[ i ] is inferred to beequal to 0. uniform_brick_spacing_flag[ i ] equal to 1 specifies thatbrick row boundaries are distributed uniformly across the i-th tile andsignalled using the syntax element brick_rows_height_minus1[ i ].uniform_brick_spacing_flag[ i ] equal to 0 specifies that brick rowboundaries may or may not be distributed uniformly across i-th tile andsignalled using the syntax element num_brick_rows_minus1[ i ] and a listof syntax elements brick_row_height_minus1[ i ][ j ]. When not present,the value of uniform_brick_spacing_flag[ i ] inferred to be equal to 1.brick_rows_height_minus1[ i ] plus 1 specifies the height of the brickrows excluding the bottom brick row in the i-th tile in units of CTBswhen uniform_brick_spacing_flag[ i ] is equal to 1. When present, thevalue of brick_rows_height_minus1 shall be in the range of 0 toRowHeight[ i ] − 2, inclusive. num_brick_rows_minus1[ 1 ] plus 1specifies the number of brick rows partitioning the i-th tile whenuniform_brick_spacing_flag[ i ] is equal to 0. When present, the valueof num_brick_rows_minus1[ i ] shall be in the range of 1 to RowHeight[ i] − 1, inclusive. If brick_split_flag[ i ] is equal to 0, the value ofnum_brick_rows_minus1[ i ] is inferred to be equal to 0. Otherwise, whenuniform_brick_spacing_flag[ i ] is equal to 1, the value ofnum_brick_rows_minus1[ i ] is inferred. brick_row_height_minus1[ i ][ j] plus 1 specifies the the height of the j-th brick row in the i-th tilein units of CTBs when uniform_tile_spacing_flag is equal to 0. Thefollowing variables are derived, and, when uniform_tile_spacing_flag isequal to 1, the values of num_tile_columns_minus1 andnum_tile_rows_minus1 are inferred, and, for each i ranging from 0 toNumTilesInPic − 1, inclusive, when uniform_brick_spacing_flag[ i ] isequal to 1, the value of num_brick_rows_minus1[ i ] is inferred, byinvoking the CTB raster and brick scanning conversion process: - thelist RowHeight[ j ] for j ranging from 0 to num_tile_rows_minus1,inclusive, specifying the height of the j-th tile row in units ofCTBs, - the list CtbAddrRsToBs[ ctbAddrRs ] for ctbAddrRs ranging from 0to PicSizeInCtbsY − 1, inclusive, specifying the conversion from a CTBaddress in the CTB raster scan of a picture to a CTB address in thebrick scan, - the list CtbAddrBsToRs[ ctbAddrBs ] for ctbAddrBs rangingfrom 0 to PicSizeInCtbsY −1, inclusive, specifying the conversion from aCTB address in the brick scan to a CTB address in the CTB raster scan ofa picture, - the list BrickId[ ctbAddrBs ] for ctbAddrBs ranging from 0to PicSizeInCtbsY −1, inclusive, specifying the conversion from a CTBaddress in brick scan to a brick ID, - the list NumCtusInBrick[ brickIdx] for brickIdx ranging front 0 to NumBricksInPic − 1, inclusive,specifying the conversion from a brick index to the number of CTUs inthe brick, - the list FirstCtbAddrBs[ brickIdx ] for brickIdx rangingfrom 0 to NumBricksInPic −1, inclusive, specifying the conversion from abrick ID to the CTB address in brick scan of the first CTB in the brick.single_brick_per_slice_flag equal to 1 specifies that each slice thatrefers to this PPS includes one brick. single_brick_per_slice_flag equalto 0 specifies that a slice that refers to this PPS may include morethan one brick. When not present, the value ofsingle_brick_per_slice_flag is inferred to be equal to 1.rect_slice_flag equal to 0 specifies that bricks within each slice arein raster scan order and the slice information is not signalled in PPS.rect_slice_flag equal to 1 specifies that bricks within each slice covera rectangular region of the picture and the slice information issignalled in the PPS. When single_brick_per_slice_flag is equal to 1rect_slice_flag is inferred to be equal to 1. num_slices_in_pic_minus1plus 1 specifies the number of slices in each picture referring to thePPS. The value of num_slices_in_pic_minus1 shall be in the range of 0 toNumBricksInPic − 1, inclusive. When not present andsingle_brick_per_slice_flag is equal to 1, the value ofnum_slices__in_pic_minus1 is inferred to be equal to NumBricksInPic - 1.top_left_brick_idx[ i ] specifies the brick index of the brick locatedat the top-left corner of the i-th slice. The value oftop_left_brick_idx[ i ] shall not be equal to the value oftop_left_brick_idx[ j ] for any i not equal to j. When not present, thevalue of top_left_brick_idx[ i ] is inferred to be equal to i. Thelength of the top_left_brick_idx[ i ] syntax element is Ceil( Log2(NumBricksInPic ) bits. bottom_right_brick_idx_delta[ i ] specifies thedifference between the brick index of the brick located at thebottom-right corner of the i-th slice and top_left_brick_idx[ i ]. Whensingle_brick_per_slice_flag is equal to 1, the value ofbottom_right_brick_idx_delta[ i ] is inferred to be equal to 0. Thelength of the bottom_right_brick_idx_delta[ i ] syntax element is Ceil(Log2( NumBricksInPic − top_left_brick_idx[ i ] ) ) bits. It is arequirement of bitstream conformance that a slice shall include either anumber of complete tiles or only a subset of one tile. The variableNumBricksInSlice[ i ] and BricksToSliceMap[ j ], which specify thenumber of bricks in the i-th slice and the mapping of bricks to slices,are derived as follows: NumBricksInSlice[ i ] = 0botRightBkIdx =top_left_brick_idx[ i ] + bottom_right_brick_idx_delta[ i ]for ( j = 0;j < NumBricksInPic: j++) { if( BrickColBd[ j ] >= BrickColBd[top_left_brick_idx[ i ] ] && BrickColBd[ j ] <= BrickColBd[botRightBkIdx ] && BrickRowBd[ j ] >= BrickRowIBd[ top_left_brick_idx[ i] ] && BrickRowBd[ j ] <= BrickColBd[ botRightBkIdx ]) {NumBricksInSlice[ i ]++ BricksToSliceMap[ j ] = i }}loop_filter_across_bricks_enabled_flag equal to 1 specifies that in-loopfiltering operations may be performed across brick boundaries inpictures referring to the PPS. loop_filter_across_bricks_enabled_flagequal to 0 specifies that in-loop filtering operations are not performedacross brick boundaries in pictures referring to the PPS. The in-loopfiltering operations include the deblocking filter, sample adaptiveoffset filter, and adaptive loop filter operations. When not present,the value of loop_filter_across_bricks_enabled_flag is inferred to beequal to 1. loop_filter_across_slices_enabled_flag equal to 1 specifiesthat in-loop filtering operations may be performed across sliceboundaries in pictures referring to the PPS.loop_filter_across_slice_enabled_flag equal to 0 specifies that in-loopfiltering operations are not performed across slice boundaries inpictures referring to the PPS. The in-loop filtering operations includethe deblocking filter, sample adaptive offset filter, and adaptive loopfilter operations. When not present, the value ofloop_filter_across_slices_enabled_flag is inferred to be equal to 0.signalled_slice_id_flag equal to 1 specifies that the slice ID for eachslice is signalled. signalled_slice_id_flag equal fo 0 specifies thatslice IDs are not signalled. When rect_slice_flag is equal to 0, thevalue of signalled_slice_id_flag is inferred to be equal to 0.signaled_slice_id_length_minus1 plus 1 specifies the number of bits usedto represent the syntax element slice_id[ i ] when present, and thesyntax element slice_address in slice headers. The value ofsignalled_slice_id_length_minus1 shall be in the range of 0 to 15,inclusive. When not present, the value ofsignalled_slice_id_length_minus1 is inferred to be equal to Ceil( Log2(num_slices_in_pic_minus1 + 1 ) ) − 1. slice_id[ i ] specifies the sliceID of the i-th slice. The length of the slice_id[ i ] syntax element issignalled_slice_id_length_minus1 + 1 bits. When not present, the valueof slice_id[ i ] is inferred to be equal to i, for each i in the rangeof 0 to num_slices_in_pic_minus1, inclusive.

The encoding apparatus and/or the decoding apparatus according to anembodiment may derive a first partitioning structure of the currentpicture, based on the partition information for the current picture(e.g., PPS information in Table 10), wherein the first partitioningstructure of the current picture is based on a plurality of tiles.

An encoding apparatus and/or a decoding apparatus according to anembodiment may derive a second partitioning structure of the currentpicture, based on the partition information for the current picture,wherein the second partitioning structure of the current picture isbased on a plurality of first partition units, and may derive a thirdpartition structure of the current picture, based on the partitioninformation for the current picture, wherein the third partitioningstructure of the current picture is based on a plurality of secondpartition units. In this regard, one of the plurality of first partitionunits may be included in the one tile, include the one tile, or be thesame as the one tile, One of the plurality of second partition units maybe included in the one tile, include the one tile, be included in thefirst partition unit, include the first partition unit, or be the sameas the one tile.

In an embodiment, the partition information for the current picture mayinclude a rectangular partition unit flag indicating whether each of theplurality of first partition units has a rectangular shape. Therectangular partition unit flag may include rect_slice_flag of Table 9above. The one first partition unit may include at least one of theplurality of second partition units. In an example, the first partitionunit may be a slice, and the second partition unit may be a brick.

An encoding apparatus and/or a decoding apparatus according to anembodiment may parse information on the total number of the plurality offirst partition units in the current picture, based on a determinationthat the value of the rectangular first partition unit flag is 1; andmay parse information on the index delta value of said at least onesecond partition unit included in the one first partition unit. In anexample, the index delta value may be bottom_right_brick_idx_delta ofTable 9 above.

In an embodiment, the first partition unit may indicate the same unit asthat of a slice, and the second partition unit may indicate the sameunit as that of a tile. In another embodiment, the first partition unitmay indicate the same unit as that of a slice, and the second partitionunit may indicate the same unit as that of a brick. In still anotherembodiment, the first partition unit may indicate the same unit as thatof a tile, and the second partition unit may indicate the same unit asthat of a brick.

FIG. 11 is a flowchart showing operation of an encoding apparatusaccording to an embodiment, and FIG. 12 is a block diagram showingconfiguration of an encoding apparatus according to an embodiment.

The encoding apparatus according to FIGS. 11 and 12 may performoperations corresponding to those of a decoding apparatus according toFIGS. 13 and 14. Therefore, operations of the decoding apparatus to bedescribed later in FIGS. 13 and 14 may be similarly applied to theencoding apparatus according to FIGS. 11 and 12.

Each step disclosed in FIG. 11 may be performed by the encodingapparatus 200 disclosed in FIG. 2. More specifically, S1100 and S1110may be performed by the image partitioner 210 shown in FIG. 2; S1120 andS1130 may be performed by the predictor 220 shown in FIG. 2; and S1140may be performed by the entropy encoder 240 disclosed in FIG. 2.Furthermore, operations according to S1100 to S1140 are based on some ofcontents described above in FIGS. 4 to 10. Therefore, an explanation forthe specific content duplicated with contents described in FIGS. 2, and4 to 10 above will be omitted or made briefly.

As shown in FIG. 12, the encoding apparatus according to an embodimentmay include the image partitioner 210, the predictor 220 and the entropyencoder 240. However, in some cases, all of the components shown in FIG.12 may not be essential components of the encoding apparatus, and theencoding apparatus may be implemented by more or less components thanthose shown in FIG. 12.

In the encoding apparatus according to an embodiment, the imagepartitioner 210, the predictor 220 and the entropy encoder 240 may beimplemented by separate chips, or at least two or more components may beimplemented by a single chip.

The encoding apparatus according to an embodiment may partition thecurrent picture into a plurality of tiles (S1100). More specifically,the image partitioner 210 of the encoding apparatus may partition thecurrent picture into a plurality of tiles.

An encoding apparatus according to an embodiment may generate apartition information for the current picture, based on the plurality oftiles, wherein the partition information for the current pictureincludes at least one of information on the number of width parsingcolumns among a plurality of columns for deriving the plurality of tile,whose information on width is parsed, information on a last widthindicating a width among the widths of the width parsing columns, whichis parsed last, information on the number of height parsing rows among aplurality of rows for deriving the plurality of tiles, whose informationon height is parsed, and information on a last height indicating aheight among the heights of the height parsing rows, which is parsedlast (S1110). More specifically, the image partitioner 210 of theencoding apparatus may generate a partition information for the currentpicture, based on the plurality of tiles, wherein the partitioninformation for the current picture includes at least one of informationon the number of width parsing columns among a plurality of columns forderiving the plurality of tile, whose information on width is parsed,information on a last width indicating a width among the widths of thewidth parsing columns, which is parsed last, information on the numberof height parsing rows among a plurality of rows for deriving theplurality of tiles, whose information on height is parsed, andinformation on a last height indicating a height among the heights ofthe height parsing rows, which is parsed last.

The encoding apparatus according to an embodiment may derive a predictedblock for a current block included in one of the plurality of tiles(S1120). More specifically, the predictor 220 of the encoding apparatusmay derive a predicted block for a current block included in one of theplurality of tiles.

The encoding apparatus according to an embodiment may generateprediction information for the current block, based on the predictionsamples (S1130). More specifically, the predictor 220 of the encodingapparatus may generate prediction information for the current blockbased on the prediction samples.

An encoding apparatus according to an embodiment may encode imageinformation including at least one of a partition information for thecurrent picture and a prediction information for the current block(S1140). More specifically, the encoding apparatus may encode imageinformation including at least one of a partition information for thecurrent picture and a prediction information for the current block.

In an embodiment, all the widths of respective width parsing skipcolumns among the plurality of columns, whose information on the widthis not parsed may be the same as the last width, and all the heights ofrespective height parsing skip rows among the plurality of rows, whoseinformation on the height is not parsed may be the same as the lastheight.

In an embodiment, the total number of the width parsing skip columns andthe height parsing skip rows may be derived based on the sum of thecolumns of the width parsing columns, the sum of the heights of theheight parsing rows, the last width, and the last height.

The encoding apparatus according to an embodiment may partition thecurrent picture into a plurality of first partition units, and partitionthe current picture into a plurality of second partition units.

In an embodiment, one of the plurality of first partition units may beincluded in the one tile, include the one tile, or be the same as theone tile; and one of the plurality of second partition units may beincluded in the one tile, include the one tile, be included in the firstpartition unit, include the first partition unit, or be the same as theone tile.

In an embodiment, the one first partition unit may include at least oneof the plurality of second partition units.

The encoding apparatus according to an embodiment may encode informationon the total number of the plurality of first partition units in thecurrent picture, based on a determination that the plurality of firstpartition units have a rectangular shape, and information on the indexdelta value of the at least one second partition unit included in theone first partition unit may be encoded.

In an embodiment, the first partition unit may indicate the same unit asthat of a slice, and the second partition unit may indicate the sameunit as that of the one tile.

In an embodiment, the partition information for the current picture maybe encoded at a PPS level.

According to the encoding apparatus of FIGS. 11 and 12 and the method ofoperation of the encoding apparatus, the encoding apparatus maypartition the current picture into a plurality of tiles (S1100), maygenerate a partition information for the current picture, based on theplurality of tiles, wherein the partition information for the currentpicture includes at least one of information on the number of widthparsing columns among a plurality of columns for deriving the pluralityof tile, whose information on width is parsed, information on a lastwidth indicating a width among the widths of the width parsing columns,which is parsed last, information on the number of height parsing rowsamong a plurality of rows for deriving the plurality of tiles, whoseinformation on height is parsed, and information on a last heightindicating a height among the heights of the height parsing rows, whichis parsed last (S1110), may derive a predicted block for the currentblock included in one of the plurality of tiles (S1120); may generateprediction information for the current block, based on the predictedblock (S1130); and may encode Image information including at least oneof a partition information for the current picture and a predictioninformation for the current block (S1140).

That is, according to this disclosure, it is possible to increase theefficiency of picture partitioning. In addition, according to thisdisclosure, it is possible to increase the efficiency of picturepartitioning, based on the partition information for the currentpicture. In addition, according to this disclosure, it is possible toimprove signaling efficiency for picture partitioning by determining thewidth (or height) of each of length parsing skip tiles among a pluralityof tiles constituting the current picture, whose information on widthand height is not parsed, based on the last width (or height) among thesignaled widths (or heights).

FIG. 13 is a flowchart showing operation of an decoding apparatusaccording to an embodiment, and FIG. 14 is a block diagram showingconfiguration of a decoding apparatus according to an embodiment.

Each of steps disclosed in FIG. 13 may be performed by the decodingapparatus 300 disclosed in FIG. 3. More specifically, S1300 and S1310may be performed by the entropy decoder 310 disclosed in FIG. 3; S1320may be performed by the predictor 330 disclosed in FIG. 3; and S1330 maybe performed by the adder 340 disclosed in FIG. 3. Furthermore,operations according to S1300 to S1330 are based on some of contentsdescribed above in FIGS. 4 to 10. Therefore, an explanation for thespecific content duplicated with contents described above in FIGS. 3 to10 will be omitted or made briefly.

As shown in FIG. 14, the decoding apparatus according to an embodimentmay include the entropy decoder 310, the predictor 330, and the adder340. However, in some cases, all of the components shown in FIG. 14 maynot be essential components of the decoding apparatus, and the decodingapparatus may be implemented by more or less components than those shownin FIG. 14.

In the decoding apparatus according to an embodiment, the entropydecoder 310, the predictor 330, and the adder 340 may be implemented byseparate chips, or at least two or more components may be implemented bya single chip.

A decoding apparatus according to an embodiment may receive a bitstreamincluding at least one of a partition information for a current pictureand a prediction information for a current block included in the currentpicture (S1300). More specifically, the entropy decoder 310 of thedecoding apparatus may receive a bitstream including at least one ofsegmentation information for a current picture and predictioninformation for a current block included in the current picture. In oneexample, the partition information may include at least one ofinformation for partitioning the current picture into a plurality oftiles, information for partitioning the current picture into a pluralityof slices, and information for partitioning the current picture into aplurality of bricks. The prediction information may include at least oneof information on intra prediction for the current block, information oninter prediction, and information on Combined Inter Intra Prediction(CIIP).

A decoding apparatus according to an embodiment may derive a firstpartitioning structure of the current picture, based on the partitioninformation for the current picture, wherein the first partitioningstructure of the current picture is based on a plurality of tiles, andwherein the partition information for the current picture includes atleast one of information on a number of width parsing columns among aplurality of columns for deriving the first partitioning structure,whose information on width is parsed, Information on a last widthindicating a width among the widths of the width parsing columns, whichis parsed last, Information on a number of height parsing rows among aplurality of rows for deriving the first partitioning structure, whoseinformation on height is parsed, and information on a last heightindicating a height among the heights of the height parsing rows, whichis parsed last (S1310). More specifically, the entropy decoder 310 ofthe decoding apparatus may derive first partitioning structure of thecurrent picture, based on the partition information for the currentpicture, wherein the first partitioning structure of the current pictureis based on a plurality of tiles, and wherein the partition informationfor the current picture includes at least one of information on thenumber of width parsing columns among a plurality of columns forderiving the first partitioning structure, whose information on width isparsed, information on a last width indicating a width among the widthsof the width parsing columns, which is parsed last, information on thenumber of height parsing rows among a plurality of rows for deriving thefirst partitioning structure, whose information on height is parsed, andinformation on a last height indicating a height among the heights ofthe height parsing rows, which is parsed last.

In one example, the information on the number of width parsing columnsmay be represented as num_tile_columns_minus1 ornum_exp_tile_columns_minus1; the information on the last width may berepresented as tile_column_width_minus1 [num_tile_columns_minus1] ortile_column_width_minus1[num_exp_tile_columns_minus1]; the informationon the height-parsed rows may be represented as num_tile_rows_minus1 ornum_exp_tile_rows_minus1; and the information on the last width mayrepresented as tile_row_height_minus1 [num_tile_columns_minus1] ortile_row_height_minus1[num_exp_tile_columns_minus1].

A decoding apparatus according to an embodiment may derive a predictedblock for the current block, based on the prediction information for thecurrent block included in one of the plurality of tiles (S1320). Morespecifically, the predictor 330 of the decoding apparatus may derive apredicted block for the current block, based on the predictioninformation for the current block included in one of the plurality oftiles.

The decoding apparatus according to an embodiment may generatereconstructed samples for the current block, based on the predictedblock (S1330). More specifically, the adder 340 of the decodingapparatus may generate reconstructed samples for the current block,based on the predicted block.

In an embodiment, all the widths of respective width parsing skipcolumns among the plurality of columns, whose information on the widthis not parsed may be determined as the last width, and all the heightsof respective height parsing skip rows among the plurality of rows,whose information on the height is not parsed may be determined as thelast height. In an example, the number of width parsing skip columns maybe derived by subtracting the number of width parsing columns from thetotal number of tile columns, and the number of height parsing skip rowsmay be derived by subtracting the number of height parsing rows from thetotal number of tile rows.

In an embodiment, the total number of the width parsing skip columns andthe height parsing skip rows may be derived based on the sum of thecolumns of the width parsing columns, the sum of the heights of theheight parsing rows, the last width, and the last height.

A decoding apparatus according to an embodiment may derive a secondpartition structure of the current picture, based on the partitioninformation for the current picture, wherein the second partitioningstructure of the current picture is based on a plurality of firstpartition units, and may derive a third partition structure of thecurrent picture, based on the partition information for the currentpicture, wherein the third partitioning structure of the current pictureis based on a plurality of second partition units. In this case, one ofthe plurality of first partition units may be included in the one tile,include the one tile, or be the same as the one tile; and one of theplurality of second partition units may be included in the one tile,include the one tile, be included in the first partition unit, includethe first partition unit, or be the same as the one tile. In an example,the first partition unit may be a slice, and the second partition unitmay be a brick.

In an embodiment, the partition information for the current picture mayinclude a rectangular first partition unit flag indicating whether eachof the plurality of first partition units has a rectangular shape, andthe one first partition unit may include at least one of the pluralityof second partition units. A decoding apparatus according to anembodiment may parse information on the total number of the plurality offirst partition units in the current picture, based on a determinationthat the value of the rectangular first partition unit flag is 1; andmay parse information on the index delta value of said at least onesecond partition unit included in the one first partition unit. In anexample, the index delta value may indicate bottom_right_brick_idx_deltaof Table 9 above.

In an example, if the first partition unit represents the same unit asthat of a slice, then the rectangular first partition unit flag may berepresented as rect_slice_flag, and information on the total number ofthe plurality of first partition units in the current picture may berepresented as num_slices_in_pic_minus1.

In an embodiment, the first partition unit may indicate the same unit asthat of a slice, and the second partition unit may indicate the sameunit as that of the one tile. In another embodiment, the first partitionunit may indicate the same unit as that of a slice, and the secondpartition unit may indicate the same unit as that of a brick. In stillanother embodiment, the first partition unit may indicate the same unitas that of a tile, and the second partition unit may indicate the sameunit as that of a brick.

In an embodiment, the partition information for the current picture isparsed at a picture parameter set (PPS) level.

According to the decoding apparatus and the operation method of thedecoding apparatus of FIGS. 13 and 14, the decoding apparatus mayreceive a bitstream including at least one of a partition informationfor a current picture and a prediction information for a current blockincluded in the current picture (S1300); may derive a first partitioningstructure of the current picture, based on the partition information forthe current picture, wherein the first partitioning structure of thecurrent picture is based on a plurality of tiles, and wherein thepartition information for the current picture includes at least one ofinformation on a number of width parsing columns among a plurality ofcolumns for deriving the first partitioning structure, whose informationon width is parsed, Information on a last width indicating a width amongthe widths of the width parsing columns, which is parsed last,Information on a number of height parsing rows among a plurality of rowsfor deriving the first partitioning structure, whose information onheight is parsed, and information on a last height indicating a heightamong the heights of the height parsing rows, which is parsed last(S1310); may derive a predicted block for the current block, based onthe prediction information for the current block included in one of theplurality of tiles (S1320); and may generate reconstructed samples forthe current block based on the predicted block (S1330).

That is, according to this disclosure, it is possible to increase theefficiency of picture partitioning. In addition, according to thisdisclosure, it is possible to increase the efficiency of picturepartitioning, based on the partition information for the currentpicture. In addition, according to this disclosure, it is possible toimprove signaling efficiency for picture partitioning by determining thewidth (or height) of each of length parsing skip tiles among a pluralityof tiles constituting the current picture, whose information on widthand height is not parsed, based on the last width (or height) among thesignaled widths (or heights).

Although methods have been described on the basis of a flowchart inwhich steps or blocks are listed in sequence in the above-describedembodiments, the steps of the present disclosure are not limited to acertain order, and a certain step may be performed in a different stepor in a different order or concurrently with respect to that describedabove. Further, it will be understood by those ordinary skilled in theart that the steps of the flowcharts are not exclusive, and another stepmay be included therein or one or more steps in the flowchart may bedeleted without exerting an influence on the scope of the presentdisclosure.

In this document, the term “/“and”,” should be interpreted to indicate“and/or.” For instance, the expression “A/B” may mean “A and/or B.”Further, “A, B” may mean “A and/or B.” Further, “A/B/C” may mean “atleast one of A, B, and/or C.” Also, “A/B/C” may mean “at least one of A,B, and/or C.”

Further, in the document, the term “or” should be interpreted toindicate “and/or.” For instance, the expression “A or B” may comprise 1)only A, 2) only B, and/or 3) both A and B. In other words, the term “or”in this document should be interpreted to indicate “additionally oralternatively.”

The aforementioned method according to the present disclosure may be inthe form of software, and the encoding apparatus and/or decodingapparatus according to the present disclosure may be included in adevice for performing image processing, for example, a TV, a computer, asmart phone, a set-top box, a display device, or the like.

When the embodiments are implemented in software in the presentdisclosure, the aforementioned method may be implemented using a module(procedure, function, etc.) which performs the aforementioned function.The module may be stored in a memory and executed by a processor. Thememory may be disposed to the processor internally or externally andconnected to the processor using various well-known means. The processormay include application-specific integrated circuit (ASIC), otherchipsets, logic circuits, and/or data processors. The memory may includea read-only memory (ROM), a random access memory (RAM), a flash memory,a memory card, storage media and/or other storage devices. That is, theembodiments described herein may be implemented and performed on aprocessor, a microprocessor, a controller, or a chip. For example, thefunctional units shown in each drawing may be implemented and performedon a computer, a processor, a microprocessor, a controller, or a chip.In this case, information for implementation (e.g., information oninstructions) or an algorithm may be stored in a digital storage medium.

Further, the decoding apparatus and the encoding apparatus to which thepresent disclosure is applied may be included in a multimediabroadcasting transceiver, a mobile communication terminal, a home cinemavideo device, a digital cinema video device, a surveillance camera, avideo chat device, and a real time communication device such as videocommunication, a mobile streaming device, a storage medium, camcorder, avideo on demand (VoD) service provider, an over the top video (OTT)device, an internet streaming service provider, a 3D video device, avirtual reality (VR) device, an augment reality (AR) device, an imagetelephone video device, a vehicle terminal (e.g., a vehicle (includingan autonomous vehicle) terminal, an airplane terminal, a ship terminal,etc.) and a medical video device, and the like, and may be used toprocess a video signal or a data signal. For example, the OTT videodevice may include a game console, a Blu-ray player, anInternet-connected TV, a home theater system, a smartphone, a tablet PC,a digital video recorder (DVR), and the like.

Further, the processing method to which the present disclosure isapplied may be produced in the form of a program being executed by acomputer and may be stored in a computer-readable recording medium.Multimedia data having a data structure according to the presentdisclosure may also be stored in the computer-readable recording medium.The computer readable recording medium includes all kinds of storagedevices and distributed storage devices in which computer readable datais stored. The computer-readable recording medium may be, for example, aBlu-ray disc (BD), a universal serial bus (USB), a ROM, a PROM, anEPROM, an EEPROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, andan optical data storage device. The computer-readable recording mediumalso includes media embodied in the form of a carrier wave (e.g.,transmission over the Internet). Further, a bitstream generated by theencoding method may be stored in the computer-readable recording mediumor transmitted through a wired or wireless communication network.

In addition, the embodiments of the present disclosure may be embodiedas a computer program product based on a program code, and the programcode may be executed on a computer by the embodiments of the presentdisclosure. The program code may be stored on a computer-readablecarrier.

FIG. 15 represents an example of a content streaming system to which thedisclosure of the present document may be applied.

Referring to FIG. 15, the content streaming system to which theembodiments of the present disclosure is applied may generally includean encoding server, a streaming server, a web server, a media storage, auser device, and a multimedia input device.

The encoding server functions to compress to digital data the contentsinput from the multimedia input devices, such as the smart phone, thecamera, the camcorder and the like, to generate a bitstream, and totransmit it to the streaming server. As another example, in a case wherethe multimedia input device, such as, the smart phone, the camera, thecamcorder or the like, directly generates a bitstream, the encodingserver may be omitted.

The bitstream may be generated by an encoding method or a bitstreamgeneration method to which the embodiments of the present disclosure isapplied. And the streaming server may temporarily store the bitstream ina process of transmitting or receiving the bitstream.

The streaming server transmits multimedia data to the user equipment onthe basis of a user's request through the web server, which functions asan instrument that informs a user of what service there is. When theuser requests a service which the user wants, the web server transfersthe request to the streaming server, and the streaming server transmitsmultimedia data to the user. In this regard, the content streamingsystem may include a separate control server, and in this case, thecontrol server functions to control commands/responses betweenrespective equipment in the content streaming system.

The streaming server may receive contents from the media storage and/orthe encoding server. For example, in a case the contents are receivedfrom the encoding server, the contents may be received in real time. Inthis case, the streaming server may store the bitstream for apredetermined period of time to provide the streaming service smoothly.

For example, the user equipment may include a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personaldigital assistant (PDA), a portable multimedia player (PMP), anavigation, a slate PC, a tablet PC, an ultrabook, a wearable device(e.g., a watch-type terminal (smart watch), a glass-type terminal (smartglass), a head mounted display (HMD)), a digital TV, a desktop computer,a digital signage or the like.

Each of servers in the content streaming system may be operated as adistributed server, and in this case, data received by each server maybe processed in distributed manner.

1-15. (canceled)
 16. An image decoding method performed by a decodingapparatus, the method comprising: obtaining, from a bitstream, at leastone of partition information for a current picture and predictioninformation for a current block included in the current picture;deriving a plurality of tiles in the current picture based on thepartition information, wherein the partition information includesinformation on a tile column width and information on a tile row heightfor uniform tile spacing; deriving a predicted block for the currentblock, based on the prediction information for the current blockincluded in one tile of the plurality of tiles; and generatingreconstructed samples for the current block, based on the predictedblock.
 17. The image decoding method of claim 16, wherein width valuesof tile columns that the uniform tile spacing is applied are derivedbased on the information on the tile column width, and wherein heightvalues of tile rows that the uniform tile spacing is applied are derivedbased on the information on the tile row height.
 18. The image decodingmethod of claim 17, wherein a value of the information on the tilecolumn width plus one corresponds to each of width values of the tilescolumns that the uniform tile spacing is applied, wherein a value of theinformation on the tile row height plus one corresponds to each ofheight values of the tile rows that the uniform tile spacing is applied,and wherein the information on the tile column width and the informationon the tile row height are obtained from a picture parameter set. 19.The image decoding method of claim 17, wherein the plurality of tiles inthe current picture are derived according a first partitioningstructure, wherein the method further comprising: deriving a secondpartitioning structure of the current picture, based on the partitioninformation for the current picture, wherein the second partitioningstructure of the current picture is based on a plurality of firstpartition units; and deriving a third partitioning structure of thecurrent picture, based on the partition information for the currentpicture, wherein the third partitioning structure of the current pictureis based on a plurality of second partition units, wherein one firstpartition unit of the plurality of first partition units is included inthe one tile, includes the one tile, or is a same as the one tile, andwherein one second partition unit of the plurality of second partitionunits is included in the one tile, includes the one tile, is included inthe first partition unit, includes the first partition unit, or is asame as the one tile.
 20. The image decoding method of claim 19, whereinthe partition information for the current picture includes a rectangularfirst partition unit flag indicating whether each of the plurality offirst partition units has a rectangular shape, and wherein the one firstpartition unit comprises at least one second partition unit of theplurality of second partition units, the image decoding method furthercomprising: parsing information on a total number of the plurality offirst partition units in the current picture, based on a determinationthat the value of the rectangular first partition unit flag is 1; andparsing information on the index delta value of said at least one secondpartition unit included in the one first partition unit.
 21. The imagedecoding method of claim 20, wherein the first partition unit representsa same unit as that of a slice, and wherein the second partition unitrepresents a same unit as that of the one tile.
 22. An image encodingmethod performed by an encoding apparatus, the method comprising:partitioning a current picture into a plurality of tiles; generating apartition information for the current picture based on the plurality oftiles, wherein the partition information includes information on a tilecolumn width and information on a tile row height for uniform tilespacing; deriving a predicted block by performing prediction for acurrent block included in one tile of the plurality of tiles; generatingprediction information for the prediction for the current block; andencoding image information including at least one of the partitioninformation for the current picture and the prediction information forthe current block.
 23. The image encoding method of claim 22, whereinwidth values of tile columns that the uniform tile spacing is appliedare derived based on the information on the tile column width, andwherein height values of tile rows that the uniform tile spacing isapplied are derived based on the information on the tile row height. 24.The image encoding method of claim 23, wherein a value of theinformation on the tile column width plus one corresponds to each ofwidth values of the tiles columns that the uniform tile spacing isapplied, wherein a value of the information on the tile row height plusone corresponds to each of height values of the tile rows that theuniform tile spacing is applied, and wherein the information on the tilecolumn width and the information on the tile row height are configuredin a picture parameter set.
 25. The image encoding method of claim 23,further comprising: partitioning the current picture into a plurality offirst partition units; and partitioning the current picture into aplurality of second partition units, wherein one first partition unit ofthe plurality of first partition units is included in the one tile,includes the one tile, or is a same as the one tile, wherein one secondpartition unit of the plurality of second partition units is included inthe one tile, includes the one tile, is included in the first partitionunit, includes the first partition unit, or is a same as the one tile.26. The image encoding method of claim 25, wherein the one firstpartition unit comprises at least one second partition unit of theplurality of second partition units, the image encoding methodcomprising: encoding information on a total number of the plurality offirst partition units in the current picture, based on a determinationthat the plurality of first partition units has a rectangular shape; andencoding information on the index delta value of said at least onesecond partition unit included in the one first partition unit.
 27. Theimage encoding method of claim 26, wherein the first partition unitrepresents a same unit as that of a slice, and wherein the secondpartition unit represents a same unit as that of the one tile.
 28. Theimage encoding method of claim 25, wherein the partition information forthe current picture is encoded at the PPS level.
 29. A non-transitorycomputer-readable digital storage medium, wherein the digital storagemedium storing a bitstream generated by a method, the method comprising:partitioning a current picture into a plurality of tiles; generating apartition information for the current picture based on the plurality oftiles, wherein the partition information includes information on a tilecolumn width and information on a tile row height for uniform tilespacing; deriving a predicted block by performing prediction for acurrent block included in one tile of the plurality of tiles; generatingprediction information for the prediction for the current block; andencoding image information to generate the bitstream, wherein the imageinformation includes at least one of the partition information for thecurrent picture and the prediction information for the current block.